From the Top Gear Team:
James May and Richard Hammond (run using the same character sheet)
Donna Noble (Post Runaway Bride, pre Smith and Jones, Best temp in Chiswick, currently the Top Gear PA)
Lady Lara Croft (Adventuress, would have been the Star in a Reasonably Priced Car if I'd had more time)
Sir Patrick Moore (Scientific advisor and musician)
Wallace and Gromit (engineering consultants)
Character generation went pretty well, except I should really have asked players to give the characters more traits. They had too few, and too many points, so often things ended up with a near certainty of success when they did something, which removed a lot of dramatic tension.
The actual adventure - which I'll probably run again, so details are behind a cut:
The adventurers are summoned to Sir James Hacker's offices at the Ministry for Administrative Affairs and told that they've been selected for a mission vital to the future of Britain - in thirty days a small asteroid is going to collide with the Earth somewhere in the near vicinity of Milton Keynes. It will probably destroy most of the city and cause huge property damage much further out. Nobody cares much until the Minister points out that the M1 passes through the total destruction area and they face years of gridlock on the motorways if the road is destroyed.
The Americans and Russians don't have time to launch a mission, and the British armed forces can't because the Health and Safety Executive say it's too dangerous. So the Ministry has arranged for the BBC to give the Top Gear team a challenge and 50,000 pounds to save Britain from annihilation... W&G are currently Britain's only lunar astronauts, so uniquely qualified to give technical advice, Sir Patrick will help with mission planning, and Lara has a reputation for problem-solving.
Amazingly, they succeeded. I'm not going to say too much about how it went, since I may want to run it again and/or write it up as fanfic, suffice it to say that Clarkson actually did moderately well in a First Contact situation, they managed to stop him from dropping the asteroid onto Paris (though they did accidentally blow up the Eiffel Tower later), Donna saved the day and/or slapped Clarkson several times, Lara Croft got to climb ropes and wear a skin-tight designer spacesuit, and The Stig went home...
Still some bugs to sort out, and I didn't get to play with the Mary Sue mechanics, but the general idea definitely has legs, and I will be developing it.