When were prime ministers banned from driving?
David Cameron revealed earlier that he hasn't driven a car in four and a half years. He's not really allowed to for security reasons, you see. So when did prime ministers stop getting behind the wheel?
The official government car service came into being in 1946, but it was the declaration of war in 1939 that changed ministers' travel habits for good.
Before this, it was only the home secretary, who was allocated a police car, that got an official motor. And for the other ministers? Well, they had to provide their own or take public transport.
But, as the country went to war, it was decided that six 20-horsepower Austin chauffeur-driven cars should be permanently at the disposal of the War Cabinet, according to Geoffrey Dudley's History of the Government Car Service.
On Her Majesty's Service
Today, the car used by prime ministers is a rather James Bond-like Jaguar; although the parallels between PMs and the 007 agent probably end there.
The leader of the opposition is the only MP entitled to an official chauffeur-driven government car who isn't a minister.
But all former prime ministers are entitled to one, too. As is, perhaps surprisingly, the prime minister's spouse - since the days of Cherie Blair.
In fact, there was a designated driver - Roy Gibbon - for the PM's other half.
However, Samantha Cameron, while making use of the official perk, reportedly requested a female driver instead, as she was more comfortable with a woman taking her children to school, according to the Telegraph.
Churchill's car assurance
When Winston Churchill became prime minister in 1940, he reportedly decided that that his 23.5 horsepower Austin chauffeur-driven car - part of a pool of cars made available to the War Cabinet - was not fast enough. And so it was replaced with a speedier 28 horsepower model. By 1941, he had upgraded to a bullet-proof War Office Humber.
Mr Churchill wasn't averse to getting in the driving seat, pictured above driving himself to the House of Commons for the State Opening of Parliament in November 1925.
Since the 1950s, prime ministers have effectively been banned from driving while in office - for security reasons that have never been made entirely clear. For security reasons.
Although the need to be accompanied everywhere by protection officers, trained in the art of driving out of trouble, will no doubt have something to do with it.
Labour Prime Minister Clement Attlee assumes the role of passenger as his wife, Violet, takes the wheel of their splendid Humber Pullman, kick-starting a 1,000-mile election tour in February 1950. In previous campaigns, the famously modest Attlee used a little Hillman Minx. Do you think they argued over who should drive?
Night of the long drives
Private car ownership soared during Harold Macmillan's "never had it so good" era and he also widened the use of government cars by junior ministers.
In this picture, the Tory PM finds himself in rather a tight squeeze, as he slots into a particularly small car on display at the 1957 Earls Court motor show, which he opened.
More room on top?
In his youth, Conservative Prime Minister John Major failed the bus conductor exam. Luckily for him, the minor setback didn't hamper his chances of reaching the highest office in the land. Fortunately he had a chauffeur-driven car service at his disposal.
Gordon Brown revealed in 2010 that, although he had a driving licence, he hadn't been behind the wheel since he was 21. In an interview with Piers Morgan, he said that after losing the sight in one of his eyes "your ability to judge distance is affected".
There are remarkably few pictures of Tony Blair behind the wheel (that we can find). But here he is enjoying a spin in an open-air Team GB car at the Olympic Games in Athens in 2004. It was definitely the weather for it!
No turning back
Talk about one-upmanship. Margaret Thatcher left other prime ministers in the shade after her tank-driving display, during a visit to British forces in Fallingbostel, Germany. After all, why settle for a car when you can ride in the turret of a tank?
And once you've driven a tank, getting behind the wheel of a bus is probably plain sailing. Here the Conservative prime minister is pictured at the wheel of the Tory battle bus during the 1987 election campaign.