One of the artworks is Saturday Night which shows a rock 'n' roll piano player in action.
Sir Billy says the character in the drawing "does that leg thing which is pure Elton".
The comedian, who is also a talented musician, toured America with Sir Elton in 1976 and says he could not believe what a performer he was.
"When I saw Jerry lee Lewis I thought it was the best thing I'd ever seen apart from Little Richard - and then I saw Elton," he says.
The drawing shows the flamboyant piano player with his leg on the keyboard and a stool overturned behind him.
"It was that point of the show where he backheeled the stool and it tumbled off the stage," Sir Billy says.
"The roadies all dived so that it didn't break."
He adds: "I saw Elton lately and he was better than I'd ever seen him.
"He's an amazing performer."




