A COUPLE OF WEEKS LATER we returned to Benfleet, the station for Canvey Island. We had visited Canvey before, when a walk around its perimeter turned out to be a stranger experience than we had expected – raised on the sea-wall, the estuary and sky equally, impossibly vast, observing the houses of Canvey from above. John, the narrator in Terry Taylor’s 1961 novel Barons Court, All Change, observed, ‘My mum’s bungalow was called “Seaview”, but you couldn’t view the sea because of the sea-wall.’ A good 13 miles around, Canvey was entirely surrounded by the wall, which was all that prevented it from becoming water too. The island within was a deep saucer, and we balanced on its rim, raised above the boats, the houses, the caravans, the sea itself.

Despite its precariousness as reclaimed land, it is thought that Canvey has been inhabited since at least Roman times. It is suggested that the Roman astronomer Ptolemy described Canvey in his map of Albion, produced during the 2nd century A.D. The map included the co-ordinates for ‘Counus Island’, which he described as ‘east of the Trinovantes’, the Celtic tribe of Essex. This may have been Canvey, which was also associated with the ‘Council Island’ where the Trinovantes met the Iceni of Norfolk, the Cantiaci of Kent and the Catuvellaini from west Essex and Hertfordshire before Boudicca’s rebellion in 60 A.D.

Canvey is an island with a defiant character, drawn from its struggle with the sea, a conflict that has sometimes turned very bitter indeed. It is no coincidence that the cadaverous patron saint of Canvey is Dr Feelgood bassist Wilko Johnson, who was diagnosed with terminal pancreatic cancer in 2013 but has, miraculously, been cured and is still alive. Canvey is an isolated place, connected by a bridge to the mainland, projecting on its own into the Thames. Before the bridge opened in 1931, it could be reached by ferry at high water or, at low water, by wading through the mud. The island had recently become the subject of media attention when it was revealed that 100 families of ultra-Orthodox Jews from London’s Stamford Hill had decided to relocate as a community to Canvey, where property was cheaper and more easily available. There was speculation over how a place associated with traditional ideas of Englishness would deal with the arrival of people whose rationale would be to live separately, next door to Canvey’s existing inhabitants.

Terry Taylor reported that ‘Canvey Island has a lonely look. Its prom, its main road, its side streets can be swallowed up by people – yet, it still looks lonely. It tries hard to look like a holiday resort, but it fails.’ The island was putting on a front, but it was no surprise if it seemed a little hollow. Only a few years before Taylor's novel, Canvey had experienced the defining, catastrophic event in its modern existence.

Thursday 29th January 1953 was the day when a depression labelled Low Z was first recorded in the mid-Atlantic. That night it merged with a second depression, Low G, south of Iceland, and began to move slowly towards Scotland. By the afternoon of Friday 30th January, a south-west wind was pushing the waters of the North Sea towards the still-deepening depression, while at the same time a new wind drove the waters of the Atlantic in from the west. By Saturday morning, Low Z had become a ‘trough of depression’ and was moving south, now chased by a high-pressure ridge, High A. The gale it brought was the strongest then recorded, reaching hurricane force across the entire British Isles. In Orkney gusts reached 125mph, while in Southampton the strength of the wind prevented the Queen Mary from leaving port.

In Essex, things did not seem right on the River Blackwater at Maldon. A police constable reported that the wind was so strong it was holding the water in place, and the afternoon tide appeared not to have gone out. High tide was still coming though, a wall of water driven down the North Sea by the pressure ridge. Alarm began to spread south around 5.30pm as the surge hit the coast, topping sea defences in Northumberland and East Yorkshire. Lincolnshire towns flooded next, and then, as the tide in The Wash rose eight feet higher than usual, defences broke south of King’s Lynn and 65 people, mostly American servicemen and their families, drowned as their bungalows were swept out to sea. In Suffolk, the surge pushed the cliffs at Lowestoft back by 40 feet.

As we reached the south-west corner of Canvey and the Thames Estuary, we saw the island at its oddest. The white weatherboarded Lobster Smack was one of the oldest buildings on the island, dating to the late 16th century and said to be the dubious inn that provided refuge to Pip and Magwitch in Charles Dickens’ Great Expectations. Across Holehaven Creek lay the giant tanks, jetties and flares of the Coryton Oil Refinery, Canvey’s long-term neighbour. Beyond, the gantry cranes of the London Gateway port, lined up on the horizon, stood larger than anything else in the landscape.

We rounded the south-west corner of the island and walked along Canvey’s prime seafront. The Labworth Café stood defiantly above the sea-wall, a piece of lean, elegant Modernism from 1933, the only building designed solo by famed engineer Ove Arup. With its round, central viewing deck, the café mimicked the bridge of the Queen Mary herself. It now peers anxiously over the concrete sea defences, which were raised in the aftermath of the Great Storm, reducing the café’s height by a storey.

Work began on the wall around Canvey in 1623, when Canvey’s landowners agreed that the tidal island, divided into two sections by a creek, would be ‘inned’ or reclaimed from the sea. Hundreds of Dutch engineers, already engaged in draining the Fens of East Anglia, built walls of clay, chalk and Kentish ragstone around the island, and constructed sluices to control the water levels. In payment for their work, many settled on Canvey. Some streets still carry Dutch names, although others were added at the turn of the century in an attempt to attract visitors to ‘Little Holland’. An 1893 article described ‘the curious impression of having sailed into a small Dutch haven by mistake,’ with Dutch eel boats putting in on their way to Billingsgate. The relationship has not always been cosy, however; in 1667, during the Anglo-Dutch War, the Dutch navy attacked the English fleet at anchor on the Medway and sent a party up the Thames to Canvey Island, where they burned houses and barns, and stole sheep.

Our route took us right back to where we started. As we crossed back to the mainland we felt that Canvey was almost trapped by its own crucial sea defences. From lower ground behind the wall, the sea itself was obscured. In Canvey an ambivalent relationship with the sea is understandable. The Great Flood hit worst of all. The storm had reached Harwich, the northernmost point in Essex, at 11pm on the night of 29th January, and it was clear that something out of the ordinary was happening. The tide had not yet peaked, but the harbourmaster reported that it was already so high that it had broken the tide gauge. News from the north had not been passed on quickly enough, and by the time the inhabitants of Walton, Clacton, Jaywick, Brightlingsea, Mersea, Foulness, Canvey, Tilbury and Thurrock heard what was coming their way, it was too late to act. When the BBC finally broadcast an alert on the midnight news, the sea had already flooded the high-water mark along the entire Essex coast, from the northern edge at Manningtree on the Stour to the Royal Docks on the Thames Estuary, where London then began. A second wave of water hit Harwich at 12.20am. By 2am the coastal towns were underwater, and sea defences breached in 839 separate places. The floods killed 307 people on land throughout the country, and a further 224 when the Princess Victoria ferry sank in the Irish Sea. One hundred and nineteen people were drowned in Essex, including 58 on Canvey and 37 at Jaywick. On the opposite side of the North Sea in the Netherlands, 1,835 people died, a disaster of a magnitude not seen since the 1400s. In Britain, Canvey Island, now entirely underwater, became the iconic image of the Flood.

The Great Flood is still well within living memory, a civic disaster which turned the world’s attention to the east of England and to the Essex coast. Hilda Grieve’s 850-page account of the floods, published in 1959, is a masterpiece of social history. She records the events of the Great Flood in precise, sequential detail. It is a compelling, horrifying read, and a quintessential Essex book which comes to a reckoning with the sea.

Grieve sets the scene with her first sentence: ‘Essex and the sea have been antagonists for centuries.’ In matter-of-fact manner, she takes as her starting point a period 3,350 million years in the past, to which ‘the formation of the earth’s crust’ could be dated. Her history of the Essex landscape builds from this point, speeding through the ages to record disastrous floods and recurring attempts to hold back the sea. Then her account slows from a grand sweep to an hour-by-hour, and then a minute-by-minute, account of events on the one day that matters.

East of Benfleet and Canvey, the coast opened out into an unmistakable combination of tidal mudflats, low marshy ground and glittering estuary waters. On a ridge above the marsh, the ruins of Hadleigh Castle appeared like the jagged landmark painted by John Constable after the death of his wife Maria, his grief reflected in the stormy setting. England was once effectively ruled from Hadleigh, which was built by Hubert de Burgh, unofficial regent to the infant king Henry III. Later, it had been a favourite residence of Edward III, and played an important strategic role during the Hundred Years' War; it is one of the earliest in a succession of defensive installations from multiple eras now to be found crumbling along the Essex coast.

The ruins now mark the grounds of Hadleigh Temple, which belonged to the Salvation Army. This was the first of several experimental communes we would encounter during our journey, and the only one still in operation. General Booth, founder of the Salvation Army, turned to new models of living as a way to help the poorest of the poor, ‘the submerged tenth’. He set up ‘farm colonies’ at Hadleigh on the Thames Estuary in 1891 and Boxted, in Dedham Vale, in 1902. Unlike the socialist and anarchist versions we would later discover, these were patrician institutions where those who had fallen into the temptations of the East End were kept well away from alcohol and prostitutes, and were given work to occupy body and mind and to prepare them for the future. At Hadleigh, the clock in the head office window bore the slogan ‘Every Hour for Jesus’.

Hadleigh is now used by the Salvation Army to provide training. At its peak, the colony was home to 500 people who worked 3,000 acres of farmland and operated a brickworks. Its purpose was not to reshape society in Britain but to export people overseas, where they could start again – an aim also pursued by union activists on the Dengie. Hadleigh was intended to prepare the destitute for a new life in the colonies and was laid out like a military compound, with officers’ quarters, a hospital, dormitories, mess hall, library and lecture hall arranged around a central citadel. Sir Henry Rider Haggard, the 19th-century adventure novelist, also carried out extensive studies as a prospective agricultural reformer, attempting to diagnose the country’s social and economic ills. He visited Hadleigh and was impressed, particularly approving of the colony’s aspirational class system, designed to incentivise good behaviour through the lure of promotion from lower to upper.

Hidden almost too low in the landscape for us to see, Two Tree Island lies between Hadleigh Marsh and Leigh Sand. It is another former landfill site, which closed in the 1970s. The island is now a nature reserve, but the toxic waste dumped there means that access had been restricted for years. The island's eponymous two trees were elms, blown down in a storm during the 1960s. Elms had once been prominent across the Essex marshlands, but have almost entirely disappeared as a result of the arrival of Dutch Elm Disease in the late 1960s. Fruit trees can now be found across the island instead – apple, plum and pear trees seeded from London’s rubbish bins.

We entered the final stretch of the Thames Estuary with the Southend seafront, which begins at Leigh-on-Sea and stretches, unbroken, for 6 miles to Shoeburyness. This was our destination, where the mysterious Essex marshes truly began. Leigh felt disconcertingly urban after the disjointed edgelands that had taken us all the way from Purfleet and Rainham Marshes. We walked into riverside Leigh: cobbled street, boats, oysters and a pub called Ye Olde Smack. The riverside is a ‘ye olde’ village, a tiny blob on the map surrounded by the rest of Leigh, a town many times its size, an octopus of avenues filled with inter-war semis. With no separation that we could discern, Leigh became Westcliff-on-Sea, then Chalkwell, Southend-on-Sea, Southchurch, Thorpe Bay, Shoebury and Shoeburyness without a pause.

The Thames is still officially river and not sea until it reaches an invisible line in the estuary, connecting Westcliff and the Isle of Grain in Kent. The boundary is also where the jurisdiction of the Port of London Authority ends and is marked with a stone on either side. On the Kent coast a small obelisk sits in the middle of nowhere, in the mud of Yantlet Creek, and is known as the London Stone. We passed the Essex version, the Crowstone, in a rather more accessible spot on the beach at Westcliff, handy for the promenade. The Crowstone Crawl is a popular route for Southend swimmers, but the stone itself, which pokes above the water even at high tide, is a replacement from the 1950s, its predecessor long retired to nearby Priory Park.

We made our way to the far end of Southend Pier, the longest pleasure pier in the world, reaching 1.3 miles out into the Thames. It is long enough to have its own train service, but its main function for us was to emphasise the width of the river mouth. At the end of the pier the Kentish shore – the Isle of Grain – felt no closer than it did from the promenade. At the foot of the pier Adventure Island is the full English of seaside fairgrounds, with surreal entertainment on an unlikely scale. Crazy golf involves playing around a full-sized helicopter and a crashed Cessna. The arcades on the promenade are enormous, with names such as New York, Monte Carlo, Electric Avenue and Happidrome. Pubs are frequent, small and, as we passed, packed, with families standing outside, drinking together. A little further along, the Kursaal appeared like a relic from an earlier age, a domed building from 1901 which had been one of the world’s earliest and largest amusement parks. Its German name dated it firmly to the pre-First World War era, when the German cultural presence in Britain had been stronger than it was now possible to imagine.

The seafront had all the classic elements of the English seaside resort but, despite its holiday atmosphere, it was also part of industrial Essex, upstream and downwind. It was in the open-air swimming pool at Southend that a young Ian Dury, later lead singer of the Blockheads, contracted polio while on a day trip from Upminster. In her poem ‘Essex Kiss’, Lavinia Greenlaw encapsulated the coastal industrial atmospherics of Southend: ‘Chewing gum and whelks, a whiff / of diesel, crocus, cuckoo spit.’

Greenlaw knows these Essex resorts with their arcades and cheap thrills, and knows the darkness that emerged when their lights failed; she grew up south of Chelmsford in the 1970s. She recalled the absolute blackness of power cuts, as well as the grey of hours spent waiting for buses or looking for a lift. ‘I think of Essex as a place you can’t get out of easily.’ Southend is out on a limb, with nowhere to go either south or east, and it feels like a place where the only choices are to remain or to return the way you came.

Further out to sea, somewhere beyond Shoeburyness, is where aerial photographs show the muddy waters of the Thames dispersing, their colour changing from brown to blue as the river meets the North Sea. Jonathan Raban, sailing around the coast of Britain in the late 1980s, reported that a line of rubbish floats just below the surface, marking the line where the tidal flow of the river peters out. He claimed to have seen a car seat there, ‘placidly swivelling on its own.’ East Anglian painter Michael Andrews’s Thames Estuary, produced in 1995 as he was dying from cancer, is part map, part hallucination; the shore is muddy teal, and men in boats of an indistinguishable era fish at the edge of reality beside a sea whose surface glows from a light shining from somewhere in the far distance, outside the frame. One of the figures stands alone in his boat, which appears to be a ferry.

As we passed into Shoeburyness, the spread of Southend ended abruptly, and the last tip of land before the coast turned north was wide open and empty, apart from the 19th-century military buildings that came into view. This was the original site of the Shoebury Garrison, commanding the mouth of the Thames Estuary. When the Crimean War broke out in 1851, the Royal Artillery School of Gunnery had been established, and a barracks, officers’ quarters, hospital and church built. Foulness has now been taken over by QinetiQ, a defence contractor that now operates the firing range for the Ministry of Defence. The site is no longer managed by the Shoeburyness Garrison. It felt strangely unresolved, with a suburban road crossing low grassland to an area of new housing and the original Royal Artillery buildings, on a scale of grandeur unmatched by anything we had encountered on our walk so far. The old army presence – parade-ground lawns, Victorian villas, buildings identified by letters and memorials – was powerful. The very edge of Essex is still military territory, although Countryside and Metropolitan house-builders had pushed a brand-new estate into one of its corners.

The original gunnery site closed in 1976, and the firing ranges are now located on the empty marshlands of the Essex Archipelago, the mysterious, semi-accessible tidal islands to the north. Foulness, the largest of all the islands, is entirely off-limits to the public, except for those willing to brave the exceptionally dangerous tidal footpath, The Broomway. We considered navigating the footpath by ourselves, but it was no longer marked out with sprigs of broom and it did not take long for us to realise we would be entirely out of our comfort zones. The nature writer Robert Macfarlane has walked this route without a guide and survived the experience. But we lacked the controlled recklessness of the true explorer, and felt only that we were letting ourselves down.

Unlike the much better-known tidal footpath across Morecambe Bay, there were no official guides to the Broomway. Far from being a tourist attraction, the public are strongly discouraged from attempting the route. The changing tides, dependent on lunar calendar and weather conditions, shifting, soft mud, and abandoned munitions make the path spectacularly hazardous; many people are recorded to have drowned on their way to Foulness. In the 1920s, before the MoD bridge was built, the Broomway was the only way to reach the island without a boat. The postman, with his pony and trap, had followed the tide out to be sure he had time to return to the mainland.

We looped back to Shoeburyness and boarded a C2C. The train slid all the way back along the estuary towards London, tracking the route we had walked. It felt essential to the logic of our project that we find a way into this most remote of locations, but we wanted to survive the experience. Not long after we returned home, I discovered an Essex couple who led occasional guided walks along the Broomway in their spare time. They were the only people who guided on the route anymore, and were close to retirement. We decided we must visit the Essex Archipelago with them later that summer, rather than braving it by ourselves. In the meantime, we would skip ahead to the next section of coast unoccupied by firing ranges: the Dengie.