Monty Python's Flying Circus is arguably the most influential comedy series ever broadcast. However, when the show first hit British TV screens on 5 October 1969, its anarchic, surreal style was not entirely without precedent.

The Pythons themselves were no strangers to the medium or each other.

Michael Palin and Terry Jones had already forged a strong writing partnership, while John Cleese (often against his better judgement) had collaborated closely with Graham Chapman on several TV sketch shows.

On guard! Dad's Army defended the traditions of the TV sitcom

Eric Idle and American animator Terry Gilliam also regularly came into the orbit of these two partnerships - in what could be considered the rather incestuous world of TV comedy writing.

Although as a team they created a style of comedy so distinctive it earned its own adjective - Pythonesque - the sextet were not alone in breaking the boundaries of light entertainment.

Audiences in the late 1960s were of course spoiled for more traditional comic fare. The popularity of sitcoms such as Please, Sir! and On the Buses proved there was still an appetite for unchallenging end-of-the-pier sauce.

Even the genteel whimsy of Dad's Army showed there was plenty of life left in character-based situation comedies with strong storylines.

Till Death Us Do Part broke many taboos

Johnny Speight's satire of working class manners, Till Death Us Do Part, broke many taboos; but beneath the strong language and social comment it remained a fairly straightforward comedy.

However, the dominance of the tried and tested comedy formula - feedline, catchphrase, punchline - was being undermined from all sides.

In sitcomland, 1969 saw the arrival of Frankie Howerd's Up Pompeii! - the story of wily Roman slave Lucio. With the comedian barrelling through his full quota of "ooohs" and "aaahs", the storylines and jokes often took a back seat.

Although seemingly a million miles away from what Python would do later in the year, Up Pompeii! arguably shared much with the show.

Written by Carry On contributor Talbot Rothwell, it departed sharply from conventional sitcom wisdom.

Howerd's way: The story took a backseat in Up Pompeii!

Howerd's scripted asides to the audience - from comments on the quality of the set, the performance of his fellow actors, to complaints about his health - served to disrupt the flow of the story. Indeed these premeditated "ad-libs" became the main focus of the series and the major source of mirth.

The TV sketch show was also undergoing change in the 1960s, with comedy writers feeling freer to tackle a wide range of issues.

The 'satire boom' - which followed the success of the Edinburgh Festival revue Beyond the Fringe starring Alan Bennett, Jonathan Miller, Peter Cook and Dudley Moore - saw politics, religion and class transformed into laughing matters.

While this abrupt break with the cosy TV comedy of the previous decade resulted in the biting satire of That Was The Week That Was and The Frost Report - to which five future Pythons contributed - the standard format of sketches stayed largely the same.

At Last the 1948 Show star Marty Feldman

John Cleese, a regular writer and performer for David Frost's mid-60s sketch show, became frustrated by the programme's format and "by the tyranny of the punchline".

In 1967 Cleese and Graham Chapman were given the chance to explore new ideas with ITV's At last The 1948 Show. Joined by future Goodie Tim Brooke-Taylor and Frost Report head writer Marty Feldman, they began to make tentative steps towards the Pythoneseque.

At Last The 1948 Show - a title inspired by a Cleese quip about the speed of decisions from TV bosses - became a show within a show.

The sketches were interspersed with links by the glamorous Aimi Macdonald - who in a voice, which Cleese describes as that of an escaped cartoon character, would pass comment on the content.

Despite these efforts to parody the format of the TV sketch show, the Pythons, who began discussing a new show at the start of 1969, were beaten to the drop by one of the greats of British comedy - Spike Milligan.

"Milligan's done it!" Spike's Q shows inspired the Pythons

Milligan, along with Peter Sellers and Harry Secombe, had revolutionised radio comedy in the 1950s with their anarchic and absurdist Goon Shows.

Using an array of sound effects and bizarre voices the team stretched the medium to its limits and in turn changed the comedy landscape for good.

In March 1969 Milligan launched an equally ferocious assault on television with the oddly titled Q5.

The series had scant regard for form of any kind - sets were left half-built, costume department tags remained on the actors' outfits and sketches were abandoned in mid stream.

"Uh-oh! Milligan's done it already!" thought Python Terry Jones.

"We learnt from Q5," he told BBC News Online. "Q5 gave us the blessing to do what we wanted to do - which was to do a show without punchlines."

However, when the Flying Circus finally took to the air in October it was clear that their efforts had surpassed Milligan's.

While Milligan's sketches often faded into incomprehensibility, the Pythons' tighter material was saved from a similar fate by Terry Gilliam's animation links.

Also having cut their teeth on Oxbridge satire, the Pythons chose their comic targets more carefully.

While their sketches about gay soldiers or obtuse officialdom still retain their charm, Milligan's broad parodies of racism and sexism - littered with slang and slurs - make uncomfortable viewing today.