Formula One newcomers Jaguar unveiled its new car at a glitzy ceremony on Tuesday as Jackie Stewart stood down as head of the team.

British drivers Eddie Irvine and Johnny Herbert lifted the lid on the new R1 car, decked in Jaguar's familiar racing green.

The glamorous ceremony was attended by hundreds of journalists and photographers eager to witness Jaguar's historic entry into the Formula One Championship.

The mood of the unveiling was dampened by Jackie Stewart's announcement he was standing down as chairman and chief executive of the racing team.

"I'm not running away. I'll stay on the board and be in the factory every week. I'll work with the drivers, I'll be part of the overall strategy and I'll attend most of the Grand Prix," said Stewart.

Stewart did his best not to let his departure take the gloss of Jaguar's big day.

The luxury car maker led the world of motor racing in the 1950s and has a one of the finest pedigree in motor manufacture but has never before competed in motorsport's toughest challenge.

Jaguar's entry into the 2000 season marked a 'new chapter in Jaguar's history and a new chapter in Formula One', said Dr Wolfgang Reitzler, chairman of Jaguar Cars.

"For more than 50 years we have been consistent winners, from Le Mans to Daytona and Monte Carlo.

"It is part of our heritage so in a certain way the race track is the spiritual home of Jaguar.

"We are now re-opening the book at a new chapter," he said.

Last June Stewart sold off the team he founded with his son Paul to Ford - owner of Coventry-based Jaguar - in a £60m deal.

The team was renamed Jaguar Racing for this season but Stewart said it was time for him to play a lesser role.

"For the last four years I've been working harder than at any time in my life.

"I've been working 18 to 19 hours a day. That really is not good for anybody. I don't think it's good for our company. I need to move over to allow the people who are really doing the job, the space to do so.

"It will also give me a lot more time, hopefully, for my five grandchildren and my lovely wife Helen."

Stewart's position as chairman will be filled by Neil Ressler, the vice-president and chief technical officer of Ford, although the company will not appoint a chief executive officer.

Stewart's son Paul will continue as chief operations officer.