Revel Horwood, who has been a judge on the BBC One show since it began in 2004, admitted on a forthcoming episode of The Sarah Millican Television Programme that he gave one unnamed contestant four out of ten by accident when he intended to award a seven.
"Because it was a low score, I then had to find as many things wrong with it as I could," he recalled.
"I remember it was a four but I wanted to give a seven, you see, so it was a bit of a disaster. It's live television – what can you do, darling?"
[Craig Revel Horwood with fellow 'Strictly Come Dancing' judge Darcey Bussell]
The Sarah Millican Television Programme returns for a second series tonight (Tuesday, January 15) at 10pm on BBC Two.
Melanie C will also appear as a special guest on this week's show.