This is Barry Humphries in a 1997 stage production of the show at the London Palladium, performing "You've Got to Pick a Pocket or Two." Who is Barry Humphries, I hear some of you call out? And why is this noteworthy? Well, the first reason (which some readers here might have glommed on to already) is that most people most likely know him, not by his real name, but instead by the name of a very popular character he has played for decades -- Dame Edna.
The other notable reason is a fun one that delves back into history. Barry Humprhies (before he began playing Dame Edna Everage) appeared in the original cast of the very first production of Oliver! on the West End in 1960!! He had a much smaller role back then, playing Mr. Sowerberry, the undertaker who buys the orphan Oliver from Mr. Bumble. (Though a small role, the character of Mr. Sowerberry has a fun song in the stage version of the show, "That's Your Funeral," but most people don't know it because the number was cut out of the movie.) So, 37 years later, Barry Humphries dropped Dame Edna for a bit and returned to the show as Fagin.
The London Palladium is a huge theater, which I suspect is a large part of the reason he's projecting SO LOUDLY in this clip. Regardless, it's great fun to see.