For Keith Moon, the buffoon prince of rock, it was an evening of uncharacteristic calm. The 31-year-old drummer for The Who and his fiancée, Annette Walter-Lax, 24, sat in a chic London restaurant with Paul and Linda McCartney after a private showing of The Buddy Holly Story. Moon, whose hotel trashings and impractical jokes cost him, by his own estimate, some $500,000 in his 14 years with the band, sipped wine and obliged admirers with autographs and kisses.

His mood had been buoyant since he returned to England last autumn, after nine months in L.A., to cut The Who's new LP, Who Are You. The group was pondering a winter tour and two films; Moon, who had been acting as the band's spokesman, was due to fly to Tunisia to film a Monty Python movie.

Earlier this year Moon had checked into a health farm to dry out from his chronic drinking. He was only halfway onto the wagon. But he seemed happy and confident when he announced at the Holly party that he and Annette were going to marry, having lived together since Moon divorced his wife in 1975.

Barely 12 hours later, Moon died in his sleep—from a drug overdose, perhaps related to medication he had taken to alleviate alcohol withdrawal side effects and his manic tendencies.

The son of a London mechanic, Moon had been one of rock's most influential and enigmatic figures since he discovered his musical gifts playing in a Sea Scout band. At 17 he added his unpredictable art—and life-style—to an already delicate mesh of egos: singer Roger Daltrey, the stud front man; lead guitarist/writer Peter Townshend, the brooding punk philosopher; and John Entwistle, the impassive and arch-precise bassist. The result was The Who, one of rock's most durable bands.

To some, Moon's offstage exploits elevated rock's notorious "road fever" to a conceptual art. Others thought him recklessly immature. He drove his Continental into a public swimming pool, wired explosives to a hotel door after the manager complained of noise, held up an airport post office with a toy gun, and climbed outside Mick and Bianca Jagger's 11th-floor Hollywood hotel room (and nearly got shot as a burglar). It was all, he explained, an extension of the fierce drumming that powered The Who's sonic assault.

"The momentum is still going when I come offstage," he once said. "The amount of adrenaline is unbelievable. To get rid of this energy I just beat on anything—objects, not people."

Even his most benign benders, though, carried intimations of self-destruction. "Keith," said Townshend, "appeared so close to blowing himself up that we became used to living with that feeling." Adds press agent Keith Altham, "He was like a racing car without brakes."

Moon regularly smoked grass, and at one point averaged two bottles of brandy and one of champagne a day. But he stayed away from hard drugs. "I don't need the kind of illusions drugs bring. The public aspect of my life is an illusion anyway."

The Who survivors plan to continue as a trio, but, mourns Townshend, "We have lost our great comedian, our supreme melodramatist."