Equinoxes only turn up for one day at a time, twice a year, in late March and late September. They were created by the evil Count Henry Blenkinsop, who took a dwarf Shetland pony and a sensible cow, cut each of them in half and glued the two front ends together, before making a sandwich out of the leftovers.

This made walking difficult for the equinoxes, until a scientist equinox called Ginger Rogers discovered that it was easy to go backwards, as long as you wear high-heeled shoes, and so long as the half that is going forwards wears patent leather army boots. So ever since then, one end of each equinox has worn high heels and gone backwards while the other half moves forward in shiny army boots.

They have a lot of trouble getting the shoes and boots on and off, and that is why you only ever see them out and about for two days in each year. Going out with their shoes and boots on is so much fun for them that they usually hire a brass band and have a procession somewhere.

As summer approaches, it is the turn of the sensible cow to wear the high heels, while the pony end bounds forward, and we call the animal a springing equinox. Then as winter comes, the pony end wears the high heels, but it often trips, which is why some people call it a falling equinox or just a fall equinox.

The rest of the year, most equinoxes stand around in a hidden field, feeding, shambling to a new spot to feed again, or with both heads turned around, it may chat with its other half. For a good gossip session, a dozen or more of the equinoxes form a circle, so both ends can look at the person they are talking to without having to contort themselves. A few of the equinoxes have made it into show business.

Busby Berserkeley was perhaps the most famous show-biz equinox and was well known for his party tricks. By eating from both ends, he could consume 5 litres of icecream in two thirds of a minute. This trick was recorded in a documentary called ‘Forty-second treat’. After performing this, Berserkeley was hailed as a cool cat. Despite this, Busby never put on weight, and when people saw him they would shout ,‘Hey, Big Slender!’

ORIGINS: Count Henry Blenkinsop made them, but it was an accident.

SIZE: The same size as half a small pony and half a sensible cow.

UNUSUAL THINGS: The two ends both like to wear top hats, which Ginger Rogers said would make them look more debonair. They often read dictionaries, trying to find out what debonair means. Most of them are fairly clumsy monsters, so it is probably good they hardly ever get out.

IS A THREAT TO: Steam comes out of all their nostrils if they are shown a picture of Count Henry Blenkinsop, so if they had the chance, they would probably threaten him. Pool sharks are frightened of equinoxes, but the equinoxes do their best and try really hard not to tread on them.

USES: They are quite good at marching, and a few of them have been able to get work in Hollywood in the crowd scenes of musicals, but they are unreliable unless the filming is done on one of the two equinox days.

HATES: They really hate atonal music, rap music, waltz music, any sort of music that you can’t march to.

LIKES: John Philip Sousa; brass instruments (even tubas); parades and processions of any sort at all. Their favourite game is Chinese Whispers, because they can slip all sorts of puns into the game. Equinoxes really like puns.

This monster is nearly always accompanied by a hairyoddity or impish brass band, so you can hear them coming. Listen for the mix of boots crashing and high heels clacking, and look out for some small things with two heads. You cannot possibly mistake them for hairyoddities, but a lively intelligent cabbage is quite similar in personality. Luckily, equinoxes are never green, unless they have been painting.