It is very odd to hear Patrick Stewart speak American. With his unmistakable rich English accent I expected everything he said to be perfectly enunciated RP. But by force of habit, he keeps referring to his Jaguar XJS as a “Jag-waar”, the way he got used to hearing it after he moved to Los Angeles in 1987.

This worked against him when auditioning for Jaguar’s North American advertising voice-over. He automatically said “Jag-waar” in the test, not knowing the company had decided it wanted to shift away from American to English pronunciation in an attempt to underline the British values of the brand. The job went to Joseph Fiennes instead.

Stewart’s love of Jaguars was strong enough to survive this knock-back. Owning one was a childhood ambition as he grew up in a poor family in Mirfield, West Yorkshire. His parents never owned a car, but Stewart clearly remembers the first vehicle he saw.

“There was so little traffic we children could set up cricket games in the street and there was only one household with a vehicle — a husband-and-wife team who each owned their own business. The wife drove a Jaguar SS and I thought it was the most glamorous thing I had ever seen. It never occurred to me I might one day own a Jaguar myself.

“I bought my XJS new in 1989. It replaced an XJ6 and I didn’t need a car as big as a 6, so when this one came along it was exactly what I wanted. The convertible version of this model is one of the most beautiful cars ever designed. Even in California, where people are used to spectacular cars, it still turns heads. And it is effortless to drive.”

When he bought the potent V12 version Stewart didn’t realise that he was purchasing a car for life, but he has never been able to bring himself to sell it. He has even put it in his will so that it will pass to his son.

However, brand loyalty doesn’t make him blind to the virtues of other manufacturers. Stewart, most popularly known as Captain Jean-Luc Picard in Star Trek, also owns a Mercedes CL 500. He takes great pleasure in its ergonomics and aesthetics, down to the finest detail.

“There is a huge satisfaction in just moving the indicator switch, for example,” he says with glee. “Every single thing you do in a Mercedes is a visual or tactile pleasure. I tell my wife not to slap at the switches, but to respect and caress them.

“In the same way I have a real horror of people slamming car doors. The thing about the Mercedes is you just give the door a little push and it closes itself. I always stay to watch that happen,” he laughs.

Stewart failed his first driving test, but didn’t care because he was enjoying taking lessons so much. From the very beginning he has always been interested in the techniques of good driving and getting the most out of the machine.

It therefore comes as a surprise that he waited until the age of 61 to try his hand at motor racing. But it has, he says, changed his life.

“I’ve only done it once, last year, but I still think about it every day. I had been fairly interested in watching but I found it hard to keep my attention on a whole race: I used to find it repetitive.

“Not any more. I’m now an addicted Formula One television watcher. I feel I’ve had a sensation of what those guys are doing. The idea of balancing a car, for example, is something I had never before thought about. Knowing at all times which wheels are heaviest on the road and which are lightest and how you can shift and change that balance using the accelerator and brake. I found it absolutely riveting.”

Stewart’s introduction to racing was a pro-celebrity event at Long Beach, California, that required four days of instruction before competing on a two-mile street circuit flanked by concrete walls.

Stewart was asked about the difference between sitting in the driving seat of a racing car and driving the Starship Enterprise. With a characteristic dry put-down he replied that with the Enterprise he never leaves Paramount studios and the most dangerous thing that can happen is that he might fall asleep under the studio lights, whereas at Long Beach he was in a fast car facing real concrete walls. And sure enough, he hit one during practice for the race.

“I enjoyed the training far more than the actual race because I was scared of hitting another wall after that,” he says. “But having had that experience it gave me great satisfaction watching Schumacher spin out the other day because I knew exactly what that feels like and I was overjoyed to find it happens to him as well.”

Los Angeles is a dangerous place to drive and Stewart can hardly go 10 miles without facing a potential incident. But he has always liked to push his cars, so now that he is armed with the knowledge of how to do it properly he’s keen to take advantage of it whenever he can.

“There is a section of Sunset Boulevard in Brentwood, just before you get to Beverly Hills, where there are three banked curves known locally as Dead Man’s Corner.

“I drive this stretch most days and I usually like to hang back and let the traffic get well ahead of me before accelerating through the curves. You can either stay in one lane or practise a racing line. But the problem is there is one house in front of a curve with a lawn sprinkler system that makes the road wet. Alas, even I have to be careful there.”

The Master Builder, starring Patrick Stewart, opened at the Albery Theatre, London, last week and runs for nine weeks

ON HIS CD CHANGER

I'm a child of the radio; I didn't own a television until I was 24. Listening to the news is still how I like to start my day and I love listening to classical radio stations.

I also enjoy the soundtracks of shows. My favourites are Stephen Sondheim's Sweeney Todd - a masterpiece - and Assassins, also by Sondheim, also fantastic, though not so well known