 Rules governing London's horse cabs had been in existence in one form or another since the 17th century, but the first Conditions of Fitness specifically written for motor cabs were introduced in May 1906 by the then licensing authority, the Public Carriage Office, which was part of the Metropolitan Police.They were written under the guidance of W. Worby Beaumont, who was recommended to the Public Carriage Office by Lord Montagu of Beaulieu.As well as laying down the 25 ft turning circle, they also demanded a 10-inch ground clearance.