The Fall And Rise Of Reginald Perrin was quite unlike most other sitcoms: it employed a serial storyline and featured adult themes of disillusionment and loss, and a central character who was on the verge of a nervous breakdown. It was also fantastically funny. David Nobbs adapted his 1975 comic novel The Death Of Reginald Perrin as the first series of this quintessentially British sitcom (it was retitled The Fall And Rise Of Reginald Perrin for paperback) and, originally, the author wanted Ronnie Barker to play the part of Perrin, a middle-aged sales executive combating a mid-life crises with flights of fantasy. Instead, he was blessed with Leonard Rossiter, who delivered an outstanding performance in the role.

The plot centres on Sunshine Desserts, a confectionery company where Perrin is a desk-bound sales executive. The business is run by C J, a powerful figure full of impressive-sounding aphorisms that, on analysis, prove meaningless, comprising a heap of mixed metaphors and clichés piled one on top of another. C J has a quality of elusiveness that makes dealing with him frustrating, for it is impossible to decipher what he actually thinks about any given subject. Most of his statements begin with the all-purpose introduction 'I didn't get where I am today by...' followed by a baffling example of what he did or didn't do to arrive at his present status. He also has a penchant for whoopee cushions, so that meetings begin with a definite air of farce.

Perrin's colleagues, Tony Webster and David Harris-Jones, are equally superficial and lacking in original thoughts, meeting any suggestion with a simple one-word platitude, 'Great!' (Tony) or 'Super!' (David), so that the only difference between them is chemical: Tony bluffs that he is one of life's great kidders, amazingly confident and about to go places, whereas David is an intensely nervous individual, with zero confidence and a perpetually sweaty disportment. The dithering company doctor is no use either: he knows nothing about medicine and lives in hope that a sick female employee might be 'feeling chesty' so that he can have an opportunity to examine the problem area.

Then there is Reggie Perrin's secretary Joan, a middle-aged bundle of simmering sexuality, fatally attracted to Reggie and liable at any moment to pounce on him. At home, Reggie's wife Elizabeth is pleasant and understanding, but it's her very tolerance and unchanging reliability that grates on Reggie and adds to his malaise. Then there is Reggie's exceedingly boring son-in-law Tom, who makes appalling home-made wine, and his wildly off-centre brother-in-law Jimmy, whose military background seems to have cast him adrift in civilian life where he appears hopelessly out of his depth, using militaristic forms of speech to explain his predicament ('No food. Bit of a cock-up on the catering front').

From episode one, Perrin's life is brain-numbingly predictable and repetitive - the train ride into London is always 11 minutes late, whatever the excuse - but there are already signs that he is going off the rails with his lapses into surreal reverse logic and a bizarre habit of visualising a hippopotamus whenever thinking of his mother-in-law. In short, Perrin, at the age of 46, is questioning the meaning of life, and going through a real and quite terrifying mid-life crisis. Gradually his brain parts company with normality and madness becomes the order of the day. In a last-ditch attempt to preserve his sanity and escape the rat-race, he fakes his own suicide by leaving a pile of clothes on a beach and walking off into the sunset. (This plot was echoed in real life when prominent British politician John Stonehouse faked his own death in identical circumstances.) Wondering what it would be like to attend his own funeral, Reggie then wears a fake beard, calls himself Martin Wellbourne and falls in love anew with Elizabeth, who recognises his true identity but, for a while, pretends otherwise.

The Fall And Rise Of Reginald Perrin proved sufficiently popular for the BBC to recommission, and Nobbs once again wrote a novel, The Return Of Reginald Perrin (published 1977), which he then adapted for a second TV series. In this Reggie soon jettisons his Martin Wellbourne persona, reveals that he's not dead and reacquaints himself with his relatives and old work colleagues. After a brief spell working at a piggery for a Mr Pelham, and warding off the advances of a dowdy spinster Miss Erith, Perrin sports a new devil-may-care attitude and launches a shop, Grot, dedicated to selling useless things, and even he is amazed when it becomes a massive global success. Reggie remarries Elizabeth, who has become a Grot business executive, and when Sunshine Desserts collapses he relocates his former colleagues at the Grot HQ. But still Reggie is numbed by routine and eerily finds himself taking on the traits and mannerisms of C J. The second series ends with Perrin, his wife and C J all faking their suicides.

The third and final book, The Better World Of Reginald Perrin (1978, once again written in tandem with the TV scripts), formed the basis of the somewhat inferior final series. Here Reggie has his most ambitious project to date: he gathers the usual crew and launches Perrins, a self-contained commune for the middle-aged and middle-class, where its members can learn to live in harmony and then set out to spread the gospel. The dialogue was still sharp but the Perrin idea seemed to have run its course and there was a distinct lack of energy about this third series. In following the first two, however, which contained some of the sharpest and funniest comedy ever aired on TV, it did have a hard act to follow.

A poor US adaptation, called simply Reggie was made by ABC in 1983, and a variation on the Jimmy character appeared in the C4 show Fairly Secret Army a year later. And then, fully 20 years after the original show, David Nobbs returned to the main theme, although this time his character (and the actor who portrayed him) had genuinely passed on...