Allen's act was typified by a very relaxed, intimate style — he would sit on a chair, smoking and holding a glass of whiskey. An atheist (according to Allen himself, "what you might call a practising atheist"), he would often make jokes about religion, particularly the Roman Catholic Church and the Church of England. Along with his seated stand-up routines, his television shows were interspersed with sketch comedy. He had a lasting influence on British comedy, and influenced many 21st century British comedians.
Allen lost part of the index finger of his left hand, after catching it in a cog. However, he told many differing stories as to how it actually happened. One version was that his brother, John (who later became a down and out), had surprised him by snapping his jaw shut when they were children, resulting in himself biting it off. Another was that it was done deliberately to avoid National Service. One explanation that he told on his programme Dave Allen at Large is that he often stuck his finger in his whiskey glass and that it was eaten away by "strong drink". Yet another of his more memorable stand-up jokes was that, when he was a boy, he and his friends would go see a cowboy movie at the local theatre, then come out all ready to play "Cowboys and Indians." Staring down at his truncated finger, he muttered, "I had a sawed-off shotgun." Once on the show he also told a long ghost story, ending with "something evil" attacking Allen in a dark and haunted house. Allen grabbed and bit the attacker, and it turned out to be his own hand.
Allen had his first television appearance as the host of the BBC talent show New Faces in 1959. In 1961 he toured England and France with a then-unknown band called The Beatles, and toured South Africa in 1962 with Sophie Tucker, whom he described as "one of the most charming and delightful performers with whom I have ever worked". While on tour in Australia in 1963, he accepted an offer to headline a talk show with Channel 9, Tonight with Dave Allen, which was popular. Allen returned to the United Kingdom in 1964 and made a variety of appearances on ITV, including The Blackpool Show, Val Parnell's Sunday Night at the London Palladium and The Val Doonican Show. In 1967 Allen hosted his own comedy/chat series, Tonight with Dave Allen, which earned him the Variety Club's ITV Personality of the Year Award. He signed up with the BBC in 1968 and appeared on The Dave Allen Show, a variety/comedy sketch series. This was followed, 1971-79, by Dave Allen at Large, which introduced his trademark solo joke-telling-while-sitting-on-a-stool-and-drinking routine. This standup routine by Allen led to handsomely mounted sketches that continued on the themes touched on in the preceding monologues.
The comedian's trademark debunking of religious, especially Catholic, ritual throughout each episode made for minor controversy which, coupled with some quite frank material, earned the show a somewhat risqué reputation. Typical routines included sketches showing the Pope (played by Allen) and his Cardinals doing a striptease on the steps of St Peter's, aggressive priests beating up their parishioners and other priests, priests who spoke like Daleks though electronic confessionals and an extremely excitable Pope who spoke in a Chico Marx type accent as he ordered Allen to "getta your bum outta Rome! New seasons of the series, which was renamed Dave Allen in 1981, were made until 1990. During the same period, Allen also made The Dave Allen Show in Australia (1975–1977) for Channel 9 in Australia.
His final series for the BBC in 1990 caused controversy because of the strong language that Allen used (in contrast to his earlier BBC series), and the matter was raised in the House of Commons. In 1993, he moved back to ITV, where he starred in its version of Dave Allen, which was to be his final regular television series.
At the end of his act Allen would usually toast his audience with the words "Goodnight, thank you, and may your god go with you", an original and inclusive toast that typified Allen's gentle style. The camera would focus on his whiskey, which via a stage effect would refill itself as the credits rolled. His hobbies included painting: his first exhibition, Private Views, was held in Edinburgh in 2001.
Dave Allen was survived by his wife of eighteen months, Karin, and three children.