People having sex, the Duchess of Kent and the captain of the Star Ship Enterprise are all in a day’s work for black cab drivers who have been voted best in the world.

Only one in five people will ever pass the gruelling exam called the Knowledge needed to become a cabbie which includes learning more than 20,000 landmarks and 25,000 streets.

Mike Tiller, of Clayhall, said: “I think people get off on being watched, I’ve had people having sex in the back of the cab. It was someone from HSBC - people walking passed were banging on the windows.”

Mr Tiller has been driving a cab for 23 years and during that time he has had everyone from supermodels to sportsman in the back of his car.

He said: “We know what we’re doing that’s what makes us the best. You can get into any black cab and you will be taken where you want to go.”

Councillor Alan Weinberg, who drove a black cab for 36 years, said that the reason British black cab drivers are so good is due to the difficult exams. He said he liked being a cabbie as you never knew who was going to get in your cab.

He said: “This elegant woman got in and asked to go to Kensington Palace, when I drove to the gates as the policeman looked into the back of the bad and he saluted and I thought ‘who’ve I got in the back of my cab? Well, it was the Duchess of Kent.”

Martin Hizer, 47, of Little Heath, said that cab driving has a long history in this country dating back to the time of Oliver Cromwell and that it has its perks.

“Patrick Stewart [a captain in Star Trek] got in my cab so I called my friend who’s a Trekkie. Patrick used to say ‘engage’ and he’d pull down his tunic and point and he did it for me!”

Black cab drivers were voted best in the world in a survey conducted by www.hotels.com.