‘Yes, Minister! No, Minister! If you wish it, Minister!’ Richard Crossman, whose diaries were such a source of insight for the sitcom. © Getty Images

‘Fact is funnier than fiction.’ Sir Frank Soskice, the Home Secretary who snubbed his own petition. © Getty Images

‘Dear lady.’ Prime Minister Harold Wilson at work in the 1970s with his personal and political secretary, Marcia Williams. © Mirrorpix

A subtle subversive Antony Jay in the mid-1970s. © UPP/TopFoto

‘Not a laughing matter.’ Leslie Chapman, the ex-civil servant who blew the whistle on bureaucratic incompetence. © Getty Images

Filming the show in October 1982. The Welsh Office served as the Department of Administrative Affairs, and, thanks to Margaret Thatcher, Number 10 served as Number 10. © Mirrorpix

Whitehall’s comic triangle; Hacker, Sir Humphrey and Woolley. © BBC

‘It’s the way she tells ’em.’ Hawthorne and Eddington sharing the stage with the real Prime Minister in January 1984. © Mirrorpix

‘Events, dear boy, events.’ The unexpected exit of Frank Weisel, Hacker’s special advisor, is about to be facilitated. © BBC

‘He will see in the life much which is not in the books.’ Antony Jay receives his Knighthood in 1988. © TopFoto

Parity, at last, with Sir Humphrey as Nigel Hawthorne is knighted in 1999. © Getty Images

The multi-talented Jonathan Lynn, pictured in 2008 at the Hungarian publication of the Yes Minister scripts. © AFP/Getty Images

Bernard Donoughue, the show’s invaluable advisor, in 2009. © Getty Images

‘Every Prime Minister needs a Woolley.’ Derek Fowlds attends the Gala Night of the stage version of the show, Yes, Prime Minister in 2010. © UK Press via Getty Images

Going to the country. Simon Williams as Sir Humphrey and Richard McCabe as Hacker in the touring version of Yes, Prime Minister. © REX/Bettina Strenske/LNP

‘What mankind really wishes to economise is thought.’ Hacker causes alarm by forming an idea of his own in the 2013 TV revival. © Geraint Lewis/Alamy