Spike Milligan, who died yesterday, was a comedy pioneer - more Dada than ha ha, writes Brian Boyd

Spike Milligan was a unique comic talent who influenced a generation of performers. Possessing a distinctive world view and a wonderful ability to deflate pomposity, he was a "gentle anarchist" whose work with the Goons and, later, on the Q television series will be remembered for its creative audacity and surreal leanings. His death at the age of 84, after several years of illness, leaves a gaping hole at the centre of British and Irish comedy.

He will best be remembered as one of the Goons - in which he performed on radio alongside Peter Sellers, Harry Secombe and Michael Bentine for many years - although many argue that his best work came in the 1970s, with Q, a largely neglected body of work that was, nevertheless, an inspiration for contemporary acts such as Vic Reeves and Bob Mortimer, Harry Hill and the Mighty Boosh.

There is also a body of inspired comic literature to contend with: books such as Adolf Hitler: My Part In His Downfall and Puckoon are remembered fondly by those who were carried away by the anarchic force of their comic prose.

The proud holder of an Irish passport - he says he couldn't bring himself to swear allegiance to the crown when the time came to renew his British one - his television appearances, whether on The Late Late Show or Michael Parkinson's chat shows, were uproarious affairs, with Milligan ad-libbing his way onto a comedy plane that most other performers could never reach. He would say anything, at any time - he once referred to his biggest fan, Prince Charles, live on television as a "little grovelling bastard".

It is his unpredictability, his mischievous sense of fun, his surreal comic mind and his devastating iconoclasm that will be most missed.

He was born Terence Milligan in 1918 in the western Indian city of Poona, where his Irish father was serving in the British army - "not from patriotism but from the necessity to stave off starvation", as Milligan once put it.

The family moved back to England when Milligan was 15, and he got his first taste of show business by playing trumpet in a jazz band - he took the name Spike from a fellow musician of the day, Spike Jones.

Conscripted at the outbreak of the second World War, he saw active service in Italy and north Africa. Once demobbed, he became a regular face at the famous Grafton Arms pub in central London. Its owner, Jimmy Grafton, was a BBC scriptwriter, and his pub was a bohemian meeting place. It was there that Milligan met up with Sellers, Bentine and Secombe.

The four had new ideas about comedy - instead of going the music-hall route, they would treat it as if it were jazz, keeping it free-flowing and open to constant improvisation. Milligan named the group "Goon" after seeing the word in a Popeye strip cartoon.

The four Goons blithely ignored the comic conventions of the day. On extreme flights of fancy, they conjured up a series of still resonant characters: Major Denis Bloodnok, Hercules Gryptype-Thynne, Neddie Seagoon, Eccles and Bluebottle. More Dada than ha ha, their scripts were in debt to Salvador Dali more than they were to Arthur Askey. They delighted in a form of bizarre wordplay and improbable juxtapositions that enthralled their fans as much as they alienated traditionalists.

The Goons soon got their own show on BBC radio; it ran for nine years, from 1951. Their ground-breaking work was frequently misunderstood as they ran up against the conventions of the day. It wasn't so much that their work contained anything that could be considered offensive, more that the BBC was worried about hidden meanings and in-jokes.

The Goons wore it as a badge of honour that the authorities made more than 30 attempts to suppress the programme, and certain scenes they conjured up, such as the House of Commons asleep, were banned. After the team dissolved, in the early 1960s - save for the occasional reunion show - Milligan continued in radio with The Omar Khayyam Show. He was also increasingly beset by mental-health problems. He suffered a series of nervous breakdowns and was diagnosed with manic depression.

A lot is made of the supposed links between Milligan's mental-health problems and his unconventional comic gift. Addressing what was always a tortuous and problematic debate, Milligan felt he was a comic writer despite his illness, not because of it.

His hard-core fans point to Q as Milligan's lasting legacy. Bringing absurdist humour to a new level, the shows veered from comic genius to offensive and weakly scripted substandard material - Milligan, like Sellers, indulged in caricatures of Asians that would now be considered vulgar and embarrassing. Watching Q again, you can see where Reeves and Mortimer got their inspiration - although they acknowledge this at almost every turn.

Away from comedy, Milligan was a political radical. A communist in his youth, he was a fervent supporter of the Campaign for Nuclear Disarmament and an active member of Greenpeace. Many in the comedy world never forgave him, however, for his surprising decision to bring his stage show to apartheid South Africa, in 1974. Milligan said he needed the money but later bitterly regretted the tour.

Married three times, with six children, Milligan was plagued by ill health in recent years, including liver failure. He was aghast to discover that he had become an institution, and he had a jaundiced view of the many awards struck in his honour. He preferred to be seen as a maverick, someone who not only broke the rules but also made up a few new ones as he went along.

How Spike saw himself

"I suppose, basically, I am very talented, but I am not personally aware of that."

Milligan on whether he believed he would go to heaven

"I'd like to go there. But if Jeffrey Archer is there I want to go to Lewisham."

Milligan on his career in the British army

"Then came the war. North Africa, promoted in the field (they wouldn't let me indoors) . . . Mentioned in dispatches: nothing positive. Just mentioned."

"He sent me a fax. It said: 'I hope you go before me, because I don't want you singing at my funeral.' "- the late Harry Secombe

"He was a great man. I think he was the godfather of alternative comedy. He was a wonderful, crazy genius." -Eddie Izzard

"His madness is so all-embracing that it stretches to create an entire world: the Milligan world." - Kevin Gildea