Motor racing-F1 great Jackie Stewart says he's done his last lap at 85

SAKHIR, Bahrain (Reuters) - Triple world champion Jackie Stewart said he had likely driven his last lap in a Formula One car after steering his title-winning 1973 Tyrrell around the Bahrain Grand Prix circuit at the age of 85.

The Scot - world champion in 1969, 1971 and 1973 - made light of the afternoon heat as he drove around at a relatively leisurely pace behind the safety car ahead of Sunday's race start.

"I would have thought that's it," Stewart, still in his racing overalls, told Reuters when asked whether that was really the last time anyone would see him at the wheel of a grand prix racer.

"You don't forget where first gear, fifth gear is. The car felt wonderful. I mean, we didn't go fast but the whole feeling of the car was great ... it was fun to do it."

Asked what he was thinking and feeling as he suited up and stepped into the car for the last time, Stewart smiled.

"'This is a problem'," he said was his immediate thought. "Getting dressed, so much stuff, everything's thermal. As if I were racing.

"Somebody made the overalls from down here (in Bahrain). Actually, I think it's the same people who build the helmets. They did a good job."

HELMET AUCTION

If Stewart was truly hanging up his helmet, he had an exceptional one to remove: a special edition signed by all 20 living champions including Ferrari great Michael Schumacher, who has not been seen in public since 2013 due to a brain injury.

Seven times world champion Schumacher's wife Corinna helped the German sign the initials MS.

As Stewart's son Mark explained, the helmet is likely to be the centrepiece of a global auction to raise funds for Stewart's Race Against Dementia charity funding research into a disease suffered by his wife Helen.

The helmet could equally go on tour, raising funds around the world.

"We're not in a rush, but we know we have something very valuable here. And you know, at the end of the season, we might be able to get a new World Champion to sign it on top of it," said Mark, the owner of the Tyrrell.

"As long as it raises money, that's the main thing.

"It's a special thing ... To get my father together with his helmet and his 1973 World Championship car is unique and a real special moment. We're all here. All his grandchildren are here to see this."

(Reporting by Alan Baldwin; Editing by Andrew Cawthorne)