Since this year has given us Harold Macmillan at the National Theatre, Doctor Who on the box and teenage delinquents in the headlines, it would be no surprise to hear that Lyons tea houses are about to make a comeback. But for a glimpse of how far we have travelled over the past half-century, nothing is more revealing than a film released 50 years ago today. Shot in an army barracks outside Guildford, it cost £73,000 to make, recouped £500,000 at the box office and made this newspaper's reviewer laugh “every now and again”. Its title was Carry On Sergeant.

Although the Carry On films are an indelible part of our shared cultural landscape, their 50th birthday seems likely to pass with no great fanfare. To be fair, Carry On Sergeant is hardly one of the great classics of British cinema. It is not even very representative of the series to which it gave its name: no Sid James, no Barbara Windsor, no jokes about breasts or bedpans, not even any excruciating puns, just a group of feeble National Service conscripts glumly square-bashing under the beady gaze of their sergeant-major. Like the black-and-white films (Nurse, Constable) that followed it in the series, it looks like a museum piece today.

Yet that first Carry On film succeeded precisely because it was so deeply rooted in a world of hierarchy, class, deference and decorum, in which Supermac could stuff his Government with dozens of relatives, and Old Etonian cronies, and cricketers were still divided into Gentleman and Players. Like other black-and-white comedies of the day, above all the marvellous Peter Sellers vehicle I'm All Right Jack, it was a cinematic two fingers to the class system, the Old Boy network and the welfare state.

Watching it now is to be reminded how seriously people took the subtleties of accent, status and authority - embodied in film after film by a stream of doctors and matrons, representatives of the nanny state.

Times Archive, 1959: Carry On Teacher

The words 'Carry On' indicate a form of humour that will not make any great demands on the audience

• Getting to the bottom of things

Background

• A 50th-anniversary appreciation of the Carry On movie

• Oh what a Carry On

• Culture: Ooh, Matron, what’s this Carry On about?

• We can’t Carry On like this any more

What set the Carry On films apart from dozens of similar comedies produced during the fag end of the Macmillan years was their sheer longevity, as well, of course, as their much-mocked but underrated troupe of comic actors. The films plodded along in fairly unspectacular fashion until 1963, when a radio sketchwriter named Talbot Rothwell took over script duties, ushering in a golden age of terrible puns, overflowing bedpans, capacious bosoms and exploding toilets. There must have been darkness behind the humour: as an RAF pilot in the war, Rothwell had been shot down over Norway and imprisoned in Stalag Luft III, where he began writing songs and jokes for camp concerts. But it was very well disguised. To modern eyes, one of the charms of Rothwell's scripts is their unstinting, infectious cheerfulness.

The other thing that distinguished Carry On films from the cinematic fare around them, especially as the Sixties turned into the Seventies, was their extraordinary innocence. That might seem an odd thing to say, given that so much of the humour turns on bowels, breasts and bottoms, but the unspoken assumption of Rothwell's scripts is that even the mildest reference to toilets or to “having it off” is hilariously shocking. In that infamous scene from Carry On Camping that everyone remembers when Barbara Windsor's bikini flies off during the aerobics session, the audience never gets to see anything. There is no nudity in Carry On films; there is no explicit sex, no swearing, no violence. Even back in the Sixties, at their high point, these were films for Sunday afternoons, not Friday nights.

Given what we know of the 1960s, it seems baffling that so many people paid good money to watch the adventures of Sid Boggle, Francis Bigger and Sir Sidney Ruff-Diamond.

But then what we know of the 1960s is badly distorted by memory, media stereotyping and the constant obsession with youth and rebellion, so that the experiences of millions of people - the sort of people who roared with delight when Sir Rodney Ffing thwarted the Black Fingernail - are often lost.

In 1968, after all, this paper's critic, John Russell Taylor wrote that to show a French film buff “all that is most reliable and permanent in popular British taste” he had picked Carry On Doctor. This was a time when people still went on seaside holidays, bought saucy postcards for their friends and cried with laughter at bawdy songs by Max Miller and Arthur Askey. Music hall was still clinging by its fingertips to the clifftops of British culture; the permissive society had not yet made it from the headlines to the provinces.

All changed now, of course, which is why perennial talk about Carry On films making a comeback is such a waste of time. The Carry On films kicked against things that are no longer taboo: with female nudity such an everyday feature of modern films, it would hardly be shocking or funny to see somebody's bikini flying off today. These were films made for an age in which attitudes were slowly changing but most people's morality remained defiantly old-fashioned, an age in which comedians coyly alluded to sex instead of wallowing in its excesses. They were films about institutions made at a time when the State was everywhere; they poked fun at authority figures at a time when doctors, matrons and shop stewards were serious and respected figures, rather than cogs in a bureaucratic machine.

And although watching Carry On Sergeant now awakens pleasant feelings of nostalgia, it also reminds us of what we lost during the 50-year rush from Macmillan to Brown. We are a more open, honest, tolerant society, but not necessarily a more civilised or polite one. What shocked and delighted those audiences would not shock or delight us; our palates are too jaded, our sensibilities too coarsened by the quasi-pornography of fashion ads and lad's magazines.

Theirs was a kinder, gentler age. Dr Nookey, Vic Flange, Darcy Pue: we miss you.

Dominic Sandbrook is the author of the histories Never Had it So Good and White Heat (both Abacus)

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