Why cab drivers have bigger brains

"Everyone knows that the black cab is a London icon, but have you ever wondered what makes London cabbies different from the rest of us?

Becoming a London taxi driver isn't as easy as you may think. Unlike other London folk who choose to take the tube or bus, drivers have to spend hours learning the city's road network for a face-to-face exam at the Public Carriage Office to get a licence to kick-start their cabbie careers.

So what exactly does this gruelling process do to their brains? Well...