Having devoted his life to the conundrums of the cosmos, Prof Stephen Hawking has left behind a mystery of his own amid the eclectic contents of his former office.
The Cambridge cosmologist, who died in 2018 at the age of 76, treasured a blackboard that became smothered with cartoons, doodles and equations at a conference he arranged in 1980. But what all the graffiti and in-jokes mean is taking some time to unravel.
