The “Confessions” series

Confessions of a Window Cleaner (1974)
Confessions of a Pop Performer (1975)
Confessions of a Driving Instructor (1976)
Confessions From a Holiday Camp (1977)

By far the most famous and well-remembered of the 1970s British sex comedies, the Confessions, along with the distinctive features, physique and mannerisms of their iconic star, Robin Askwith, have come to be seen by many as the very definition of the sub-genre.
They marked the first and most successful attempt by a major studio (Columbia) to muscle in on a hitherto scuzzy and bargain basement industry, resulting in a strong infusion of well-known faces (who might hitherto have refused to be seen dead in any such thing) and basic but effective comedy. (Among the many guest stars, John Junkin, Liz Fraser and Linda Hayden distinguish themselves by each appearing twice in different roles; the latter, Askwith's on-off real life girlfriend, is the sympathetic female lead in the first, and a phoney French-accented member of the background crumpet assortment in the last.)
And they were, for a while, phenomenally successful: pitched as Carry On films in which you can actually see the breasts and pubic hair of the female stars, they effectively ended the Carry On series as a going concern, which tried vainly to catch up with the new mood before dying of embarrassment.
Ironically, however, the Confessions themselves came to an end not long after, after only four titles, partly because it is the fate of all radical innovation to become commonplace in the blink of an eye, but also because the set-up of the films was too restricting and allowed for only superficial variation, whereas the Carry Ons had established a format where the usual cast and jokes can be inserted into any imaginable modern, historical or fantastic framework. With the Confessions, audiences soon tired of the limited formula, and a slew of imitations (such as Stanley Long's Adventures series) staled the whole concept in quick time anyway.
Each film concerns Lea's brother-in-law (Anthony Booth, Tony Blair's father-in-law) starting some new business, which Askwith's Timmy Lea does his accidental best to ruin with a combination of slapstick sexual misadventure and goonish physical ineptitude. The reappearance each time of his family (father Bill Maynard, mother Doris Hare - Dandy Nicholls in the first film - and sister Sheila White) add to the saminess of the films, and hastened their demise, though Maynard invariably provides the most substantial laughs.
Watched en masse, there are a few surprises in the films. The popular image of Askwith's character - a randy and absurdly successful lothario who scarcely has to look at a woman to end up bashing about on the floor with her - only really comes to be in the first sequel. Confessions of a Window Cleaner, Val Guest's original film is - by the standards of the rest - an oddly sincere character comedy about a young man's coming of age, with only a small number of more-explicit-than-usual sex scenes to distinguish it from the likes of Here We Go Round the Mulberry Bush. Timmy is a virgin when we first meet him, and a gauche and nervous sexual inadequate thereafter, who is taught technique and confidence by the experienced older women - those habitual oversexed housewives of seventies comedy - he meets on his daily rounds. (His soap suds-drenched scene with Sue Longhurst is perhaps the most famous of the series.) But he almost immediately falls in love with Linda Hayden's young policewoman, and finishes the film within an inch of getting married.
It's the second film, Confessions of a Pop Performer (directed like the rest by Norman Cohen), that perfects the formula. (Also in its favour is a good supporting cast of comic players, as well as some funny pop songs that represent the height of musical degeneracy in the last few minutes before punk, when rowdy delinquent pop oiks still can, and do, play piano.)
But the limitations of the set-up are already looking fatal by the time of Confessions of a Driving Instructor, which plays as a series of unconnected chunks held together with gossamer - boring and increasingly irrelevant sex scenes, comedy turns from Maynard and Windsor Davies, broad physical slapstick.
Ironically, it's the last in the series, Confessions From a Holiday Camp, that gets the mix right: the situations are reasonably funny, there are a few genuine laughs, the regular characters are integrated legitimately, and even the sex scenes have some basis in the narrative and pay off comedically.
But despite the climactic captions advising audiences to avoid imitations, and a closing narration from Askwith indicating yet another adventure, after this Timmy Lea confessed no more.