There is a story that Rick Wakeman, the former titan of progressive rock, likes to tell about the fans he has acquired since he became a jobbing TV wit. “I was doing my solo show, telling stories and playing the piano. Afterwards this elderly woman who’d seen me on Countdown says: ‘You were very good. I had no idea you played the piano. Have you made any discs?’

“I say: ‘Yeah, 136.’

“She says: ‘And have you sold them all yet?’ ”

Wakeman chuckles (and for an official Grumpy Old Man he chuckles a lot). “There was really nothing you could say.”

It is, though, half a lifetime since Wakeman, resplendent in cape and Kate Moss haircut, fired up his Moog synthesizer and invented “symphonic rock”, a faintly preposterous mix of classical chords and rock backbeat. His album Journey to the Centre of the Earth sold 14 million copies; The Myths and Legends of King Arthur — staged on ice — became prog rock’s defining folie de grandeur. He made a mint, then he lost it — thanks in part to his energetic hedonism, in part to the unwonted arrival of punk.

But in British life there’s not much that doesn’t come back into fashion — Spandau Ballet, stagflation, even the Tory party. So here in 2009 is a hale, hearty Wakeman talking about his biggest British blow-out since King Arthur — two open-air performances of The Six Wives of Henry VIII. They are being mounted at Hampton Court in honour of the 500th anniversary of Henry’s coronation. Wakeman is promising spectacle, surprises, a narration by Brian Blessed and “silly hats”.

“In 1973, when we launched the album, I asked to do a show there. But Hampton Court flat-out refused. It was like I’d committed treason just by asking. This time they asked me.”

Wakeman says that when planning the shows he had learnt from experience to ask for too much, “because it always gets watered down.

“I said I’d like a full symphony orchestra, the English Chamber Choir, a big band, loads of effects, a massive stage and some lute players walking in the crowd. I gave my little speech, sat down, then the man in charge said: ‘I think that’s all do-able.’ I thought: ‘That’s not how the script usually goes’.”

Two banks were due to sponsor the shows but both pulled out as the credit crunch deepened. Wakeman, who is ploughing his own money into it, admits that there are risks — staging an outdoor evening event in Britain at the start of May is meteorologically optimistic for a start. He has 10,000 tickets to flog but assures me that they are going fast. “The interesting thing is that we know more than 1,000 people have bought tickets from abroad. People are coming from Japan, Russia, Australia.”

The pianist may have attended the Royal College of Music but is more P. T. Barnum than Prokofiev and is relishing the chance to dust off the sparkly cape. Failure isn’t an option. “I’ve done this before. People said, ‘Oh Arthur on ice, it was nuts, it cost you a fortune. Yeah, it did, but up to that point we’d sold 3 million copies of the album and within six months of doing it on ice we’d sold 14 million.”

Wakeman has always been larger than life — three wives, two heart attacks while in his twenties, a prodigious booze habit until he gave up in 1985 (onstage with Yes in the early Seventies he played with optics of brandy and whisky fixed to his Hammond organ and, more often than not, a keg of beer beside it). He’s bundled up a bunch of on-the-road anecdotes into his latest book, Grumpy Old Rock Star. The stories range from the sublime — playing an antique harpsichord for the grand dame of the Chandon champagne dynasty in her château — to the cor blimey, such as band members mooning over the poppadoms in a Maida Vale curry house.

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