English quizzer David Stainer disagreed with Labbett, who said only knowledge of four bits of data was needed to guess the correct answer.
"If you knew four you'd either identify the pair or know the pair must be the fifth," he said.
Labbett, 54, said he "would have never have gone" for the correct answer, which was Marilyn Monroe. Queen Elizabeth II and Monroe were both born in 1926.
According to Express, the contestant opted to not risk getting the question wrong, and instead pocketed 500,000 pounds – $950,000 New Zealand dollars.
It's the latest controversy for Who Wants to Be a Millionaire, following Jeremy Clarkson being branded a 'wasted lifeline' after giving a contestant a wrong answer when she used her "Ask a host" lifeline.
The Chase airs Monday to Saturday on TV 1.