Royal Wedding: Cake Store Audition

VIDEO: Nick Watt searches for clues to who will bake William and Kates wedding
WATCH Royal Diary: Who Bakes the Cake?

Today marks a royal audition, and it's the cake stores that are in the spotlight.

The part they're all going for? Baker of the royal wedding cake.

"The making of it and the delivering of it would be a daunting task but we would certainly have a go," said Steve Howard, creative director at the Cake Store in London.

Daunting, even for the biggest wedding cake maker in the land. They're not afraid of a chocolate-covered coronet, piping, ribbons, top hats. They have 13 decorators on staff.

But the prospect of a royal wedding cake is something different.

"The responsibility of providing a cake for such a big event ... all the crests and coats of arms," Howard said.

Presumably, the cake is destined for the 300 guests at the palace dinner hosted by Prince Charles.

"A fruit cake is more traditional as a wedding cake, although it is very heavy and rich," Howard told ABC News.

"I think maybe a younger couple like Katherine and William would like something like a chocolate fudge cake, something more modern."

British custom has it that the bride and groom cut the cake together. It's a wedding high point.

The part where bride and groom smear it over each other's faces, though, has do place here. As Nick Watt said recently on "Good Morning America," "We think that's a bit weird."

As with Kate Middleton's wedding dress, discretion is the name of the game.

"I wouldn't be allowed to say, even if we had been asked ... to bake Kate and William's wedding cake, I'm afraid," Howard said.

And it's not just the creative director who's secretive: "We could not possibly comment," said Tim Slater, co-owner of the Cake Store. "It's protocol."

Well, because they won't comment, we'll have to look into other options. Being a military man himself, Prince William may well choose a military baker for the job.

That's what Prince Charles did when he married Diana in 1981.

David Avery, a now-retired navy baker, made their cake.

Diana's Baker Has Retired

"You can't get no higher than that," Avery told ABC News. "I could tell my wife and family, but no one else.

"I had to go to Buckingham Palace to see Diana and I had a blueprint," Avery recalled. "It was my idea and had to look back in history, round one, square one."

"She said, 'Yes,'" he said. "She wanted a wedding cake, not a monument."

Avery's recipe came from his mother. And, yes, the ingredients are a secret.

But count Avery out of the running for next month's royal wedding. He's retired.

But his secret recipe is still in high demand. Avery saved a piece of the cake as a memento, and recently sold a slice on eBay for $1,500.