There aren't many sitcoms successful enough to not only produce spin-offs that eclipse the popularity of the original, but also go on to produce American remakes that run for more than double the number of series. But there is at least one: for this week's Comedy Rewind, we take a closer look at the lasting legacy of Man About The House.

By 1973, Brian Cooke and Johnnie Mortimer were already sitcom stalwarts, having written episodes of radio comedy The Men From The Ministry before going on to pen the fourth series of Round The Horne with Barry Took and Donald Webster. Their next step was to create their first sitcom for television, Thames's Father, Dear Father, before returning to the world of Round The Horne on BBC radio, this time with Kenneth Williams as the star of Stop Messing About.

After their now almost completely forgotten Peter Butterworth and Peter Jones sitcom about a second rate escapologist, Kindly Leave The Kerb, the first seeds of Man About The House were sown with their next endeavour: Alcock And Gander was their first collaboration with Richard O'Sullivan, who starred alongside Beryl Reid.

O'Sullivan was himself becoming a recognisable face - a former child actor finally finding his feet as an adult in the industry - having starred in both Doctor At Large and Doctor In Charge, as well as Barry Cryer and Graham Chapman's Now Look Here..., alongside Ronnie Corbett.

Back working with ITV's London weekday broadcaster Thames Television, when Man About The House began in 1973, the premise alone was controversial: two young women - forthright, confident Chrissy, played by Paula Wilcox, and the sweet natured Jo, played by Sally Thomsett - are desperate to find a flatmate with whom they can share their bills, and, mistaking cookery student Robin for a girl, offer him the room.

What could have so easily been the basis for a sex comedy in the vein of Robin Askwith's Confessions series, or even his later sitcom vehicle, Vince Powell's Bottle Boys, instead trades on the strong character writing of Cooke and Mortimer, who make sure that the barbed banter between Chrissy, Jo and Robin is always good natured and never too salacious. In fact, it is made clear that Chrissy and Jo are very aware of the dynamic that could develop and are in complete control over their randy male flatmate.

Wilcox came hot from her success, starring alongside Richard Beckinsale in Jack Rosenthal's The Lovers, while Thomsett was known for her film roles in The Railway Children (which she appeared in aged twenty despite playing a character who was eleven), and Sam Peckinpah's controversial thriller Straw Dogs. This is referenced in the first episode of the second series when Chrissy, attempting to chat up a character played by Ian Lavender, asks if her dress "gives me the look of Susan George?" to which Lavender claims that he auditioned for Straw Dogs, but that "Peckinpah and I just didn't hit it off".

The other central characters are landlords George and Mildred Roper, as played by Brian Murphy and Yootha Joyce, respectively the henpecked husband and domineering wife. A typical side plot would see George attempt a money making scheme whilst trying to hide it from Mildred, who inevitably discovered it in the end and made him pay. Murphy and Joyce developed into a kind of double act, with Joyce becoming famous for her perfect timing of biting one liners and Murphy's endless variety of double-takes and awkwardness around Mildred's wanton desires, resulting in the first and most successful of the sequel sitcoms, George & Mildred. Their popularity was such that, O'Sullivan, Murphy and Joyce all starred in Cinderella, the 1976/77 London Palladium pantomime.

Other regular characters included Doug Fisher as Robin's lascivious, laddish friend Larry, who eventually rents the attic space above their flat, and Roy Kinnear as George's equally unlucky friend Jerry, who is the only other character to reappear in George And Mildred. Daphne Oxenford played Chrissy's mother, while Dennis Waterman and Janine Duvitski made single appearances in very early roles.

Man About The House was a near instant success, its mix of frustrated-permissive-society plots, loveable characters and plain laugh-out-loud funny writing proving a winning combination with ITV audiences.

Hammer Film Productions had a hugely successful run of sitcom-to film adaptations through the first half of the 1970s, including the On The Buses series, Nearest And Dearest, Love Thy Neighbour and, perhaps most surprisingly, the now long forgotten BBC sitcom That's Your Funeral, starring Bill Fraser. Man About The House was the last such endeavour, made by Hammer in 1974, just one year after the launch of the TV series: the plot follows the same structure as the series, with the stakes raised by the prospect of a property developer buying every house on their street for regeneration.

Perhaps the most notable aspect of the film from a comedy fan's perspective are the sheer number of cameos. Not only does Arthur Lowe play the ruthless property developer, but the climax of the film takes the cast to a television studio in order to stop George from signing away the house, where we are treated to a glut of appearances in quick succession, from a surreal speech by Spike Milligan to a cleverly written scene in which Love Thy Neighbour stars Jack Smethurst and Rudolph Walker argue about chess. When George embarrasses himself by directing racist language at Walker, Smethurst comes to Walker's defence.

Back on television, Man About The House concluded in April 1976, having accumulated an impressive 39 episodes over six series. Despite pining after Chrissy throughout the run, Robin eventually loses her to his brother, Norman, played by Norman Eshley. The final episode saw the pair marry and leave the flat: Eshley went on to play the central role of neighbour Jeffrey in George & Mildred.

George & Mildred began just five months after Man About The House ended, in 1976. Murphy and Joyce reprised their roles, as they attempted (or in George's case, were forced into) social mobility, moving from central London to a house in the more upmarket area of Hampton Wick. Much of the comedy came from the culture clash, with Mildred trying to fit in - particularly with genteel, Conservative-voting next-door neighbours Ann and Jeffrey - while George is completely unbothered.

Quickly exceeding the popularity of its parent, the series proved so popular that Cooke and Mortimer wrote a spin-off stage play that toured the UK and Australia, and a film version was released in 1980 (with In Loving Memory writer Dick Sharples taking over writing duties). However, unlike its counterparts, reception to the film was so overwhelmingly negative it is often cited as marking the death knell of sitcom-to-film adaptations. It would be another six years before another adaptation hit cinemas, in the form of David Renwick and Andrew Marshall's reworking of Whoops Apocalypse in 1986.

On television however its success was undimmed, and scripts were already written with filming due to begin on the sixth series when Joyce died in August 1980, having struggled intensely with alcohol abuse in private for many years. Murphy went on to star in L For Lester on the BBC in the following year before reuniting with Cooke and Mortimer for The Incredible Mr Tanner alongside Roy Kinnear, a remake of their earlier series Kindly Leave The Kerb.

Robin's Nest, meanwhile, followed Robin as he pursued his career as a chef with new girlfriend Vicky, played by O'Sullivan's real life partner at the time, Tessa Wyatt. In what feels incredible to modern eyes and ears, Cooke and Mortimer actually had to gain special permission from the Independent Broadcasting Authority in order to portray Robin and Vicky as common law partners, something never shown in a British sitcom. O'Sullivan also wrote the theme music for the show - it was arranged by The Shadows drummer Brian Bennett, with whom O'Sullivan had previously co-starred in two Cliff Richard films - 1961's The Young Ones and 1964's Wonderful Life.

Also in the series was David Kelly (the genial Irishman best known as builder O'Reilly in Fawlty Towers), as one-armed cleaner Albert, and the show even featured Bond girl Honor Blackman as Vicky's mother Marion, later replaced by Barbara Murray.

The show ran for six series and forty eight episodes from 1977 to 1981, more than either Man About The House or George & Mildred. Cooke and Mortimer only wrote the first two series before gifting the show to other writers, returning to write the first episode of Series 6. Peter Frazer-Jones directed every single episode of all three sitcoms, as well as the George And Mildred film.

As with many sitcoms of the time, an American version of Man About The House was quickly mooted once its success in Britain was established. Initially under the stewardship of M.A.S.H creator Larry Gelbart and ABC executive Fred Silverman, the show that would become Three's Company was fully developed by Don Nicholl, Michael Ross, and Bernie West, the writers who previously adapted Johnny Speight's Till Death Us Do Part to huge success as All In The Family. Like the original, the series quickly proved massively popular with the public, running for eight seasons and making stars of John Ritter, Joyce DeWitt and Suzanne Somers. It even mirrored its counterpart, producing spin-offs The Ropers and Three's A Crowd, based on George & Mildred and Robin's Nest, respectively.

It is fair to say, therefore, that Man About The House may well be one of the most important British sitcoms in terms of its impact worldwide. Domestically it also launched or cemented the careers of the three central actors, Thomsett being the only one who dropped out of acting not long after, only appearing sporadically in plays and pantomimes.

O'Sullivan starred in several further sitcoms, perhaps most notably Me & My Girl, which ran for four series from 1984-1988, before retiring in the 1990s due to declining health. Wilcox went straight into another sitcom, Miss Jones And Son, before appearing in several dramas, occasionally returning to star in sitcoms like Fiddlers Three opposite Peter Davison and, more recently, titles such as Upstart Crow and Trying. She and Brian Murphy remain in-demand comic actors to this day.

But, to the generation who grew up with it, the sharp writing and cosy chemistry the quintet shared in Man About The House and the sitcoms that follows it will be their defining legacy.