Former Rolling Stones star Bill Wyman may have just cost memorabilia auction bosses thousands by revealing the band's signed keepsakes might not be 100 per cent authentic.

In a new Rolling Stone magazine interview, the old rocker admits he and his bandmates didn't have time to hand round posters and books before gigs for each member to autograph individually, so they learned to forge each other's signatures.

Wyman admits he often chuckles when signed items from the mid-to-late 1960s come up for auction - because he knows they're not quite what they seem.

He explains, "There's footage of us signing things in the dressing rooms. We all tried to do it. And there were stacks and stacks of autographed books, programmes to be signed, and we just used to grab a bunch each and sign everybody's name.

"We all learned to sign each other's signatures. Except for Charlie. He wouldn't sign anything. But me, Keith, Mick and Brian all could sign each other's autographs.

"When I see them now for sale, I know that, you know, two of them are not theirs - originals and all that. But it was the only way to do it, because you couldn't pass this stuff around. You didn't have time. You were onstage in 10 minutes."