'Rock and roll, the beginning of the end," wails Frank Parr, the traditional jazz trombonist and former Lancashire wicketkeeper, in the second of George Melly's autobiographical volumes, Owning Up (1965). It is the mid-1950s, and Parr has just heard the ecstatic screams of an audience of teenage girls greeting Britain's first rock star, Tommy Steele - the same audience that has sat with silent indifference through a first half played by a mystified Parr and Melly with trumpeter Mick Mulligan's Magnolia Jazz Band.
The musicians were discovering that traditional jazz, which had been a hot ticket with young audiences for both listening and dancing in the decade after the second world war, was on the way into history books and the world of buffs. But Mulligan, who has died of a stroke aged 78, grabbed enough excitement and hot music-making from the idiom's heyday to last him a satisfied lifetime. They called him "king of the ravers", and a good many women and pub landlords he ran across in his 1950s and early 60s roadlife can probably remember why.
Maybe it is hard to imagine now that men like Melly and Mulligan could have occupied their own iconic place for British youth in the early postwar years - with their baggy-jumpered, marketing-indifferent, boozy English amateurism, and their devotion to a New Orleans and Chicago jazz method that had been invented a quarter of a century before. But they crucially contributed to the revival of a jazz that reached out to a wide audience with its earthiness, humour and the forthright passions of the blues.
Mulligan was born in Harrow, Middlesex, and educated at the Merchant Taylors' school, Northwood. After national service as an officer in the Rifle Brigade, he fleetingly entered the family wine-importing business on demobilisation - but was eventually paid a salary by his cousins to stay out of the business and stop sampling the stock.
Fired by that almost religious enthusiasm for early American jazz and blues widespread in Europe after the war, Mulligan taught himself the trumpet in a manner approximating Louis Armstrong's, and formed the Magnolia Jazz Band, with Melly singing Bessie Smith songs in front.
The bands of Mulligan, Ken Colyer and Humphrey Lyttelton soon became the standard-bearers for authentic New Orleans and 1930s-Chicago styles - with Colyer's uncompromisingly devoted to the former - though the Magnolia Band later evolved toward the vivacious approach of Chicagoan Eddie Condon as the quality of its musicianship unsteadily improved.
A series of recordings for small labels, and a few years of broadcasts, television shows and busy touring followed - featuring an almost-terminal coach crash, and sexual and alcoholic experiments worthy of the rock bands that were to replace them - before the Magnolia band broke up in 1962. Melly went solo, but Mulligan gave up playing full time, moving to Pagham in Sussex to run a grocery and off-license business.
His first wife, Pamela, died in 1976, and in 1980 Mulligan married Tessa Howard. He occasionally played as a guest with other bands during the 1970s, but principally devoted himself - as both a fan and a successful owner - to horseracing, another abiding passion of his life.
Bohemian, disrespectful, charming, forthright, and - for all his disarming casualness about rehearsal or practice - an awed disciple of the great jazz pioneers all his life, Mulligan was the kind of jazz eccentric for which the mould no longer exists.
He is survived by his second wife Tessa, by his two sons and two daughters from his first marriage, and by three stepdaughters.
· Peter Sidney 'Mick' Mulligan, musician, born January 24 1928; died December 20 2006