Albert Einstein's theory of royalty longevity

It's no surprise to see Elvis Presley, John Lennon and Marilyn Monroe on a list of the top 10 highest earning deceased celebrities, but what's Albert Einstein doing there?

He's been dead for 53 years, but Einstein's estate still brings in a whopping $18m (£11.2m) every 12 months, putting him fourth in the annual ranking compiled the by the US finance publication Forbes.

The latest version of the list puts only Elvis Presley, the Peanuts cartoonist Charles M Schulz and the actor Heath Ledger above him. Ledger's financial legacy is boosted by percentage deals linked to his role as the Joker in Batman film The Dark Knight.