George Melly, the jazz singer, author, and raconteur who died yesterday at age 80, leched, drank, and blasphemed his way around the clubs and pubs of the British Isles and provided pleasure to the public for five decades.

Melly’s involvement in jazz was born out of a romantic nostalgia for a golden age of brothel music. Appearing in the 1950s with Mick Mulligan’s Magnolia band and later for nearly three decades with John Chilton’s Feetwarmers, “Good Time George” followed a well-established routine of singing numbers from the 1920s (his foremost influences being Bessie Smith, Fats Waller, and Jelly Roll Morton) interspersed with camp asides and bawdy anecdotes.

Loopy-mouthed and rotund under an outsized fedora, Melly could always be relied upon to wear louder suits and tell better, funnier, and dirtier jokes than anyone else on the circuit. With a smile once described as “a cross between a leer and a twinkle,” he pushed hard at the boundaries of public taste, knowing that, like the errant schoolboy he once was, he would always be forgiven. “I have this ability to appear outrageous without paying the consequences for it,” he observed.

Melly went through periods of colossal excess. When he and John Chilton began their annual Christmas season at Ronnie Scott’s in 1973 (the first of a series of Christmas bookings that ran for more than a quarter of a century), Melly’s performances had a uniquely erratic quality: “The captain is no longer in command of the ship,” was one of John Chilton’s more diplomatic announcements as Melly, one night, slumped down the microphone stand on to the deck.

Along with his drinking, his sexuality (about which he was remarkably candid) became inseparable from his public image. Beginning with mutually satisfactory fondlings beneath the desks at prep school, he proceeded at Stowe, and in the lower decks of the Royal Navy, to a life of enthusiastic homosexuality; though when the former editor of The Sunday Telegraph, Sir Peregrine Worsthorne, claimed to have been seduced by Melly on the Stowe art room sofa, Melly denied the charge: “I seduced many young men,” he conceded, “but he was years older, so I wouldn’t have dared.”

Despite these Bohemian urges, Melly had been born with a strong instinct for self-preservation: “I didn’t carry my romanticism to the point of an early grave,” he once acknowledged. “My own middle-class background came and reclaimed me before it was too late.” After being seduced by Sybil Mesens, the wife of the surrealist ELT Mesens, he became “absolutely devoted to heterosexuality,” a conversion confirmed by 44 years of more or less happy marriage to his second wife Diana.

His heroic consumption of alcohol took longer to renounce, but from the early 1980s, when he changed a bottle of brandy a night for a bottle of wine, Melly could generally be relied upon to stay upright for the duration of a performance, although his act remained as unpredictable as ever. There was, though, a serious side to the funster and jazz singer.

Surrealism, along with jazz, was the great passion of Melly’s lifeand he lectured and wrote extensively on the subject. But lewdness was never divorced from scholarship, and serious research was always spiced with saucy anecdotes about encounters with prostitutes and seedy metropolitan low-life.

In addition to his three volumes of autobiography, Melly’s books included “Revolt Into Style” (1970), in which he explored the role of pop music as a bridge between rebellious adolescence and maturity; “The Media Mob” (1980, with Barry Fantoni); “Tribe of One: Great Naive and Primitive Painters of the British Isles” (1981); a biography of Scottie Wilson entitled “It’s All Writ Out For You” (1986), and a scholarly study (with Michael Woods) of Paris and the Surrealists (1991).

George Melly is survived by his wife Diana, by their son, and by a daughter from his first marriage.