Steve McQueen was among the biggest gearheads the movie industry has ever seen. Not only did he promote motorsports through movies like On Any Sunday and its four-wheeled equivalent, LeMans, but he was also an active enthusiast and participant himself. His love of things that go fast was his inspiration behind these movies, unlike other movie gearheads like Paul Newman and Tom Cruise who found theirs while preparing for movies.
McQueen had previously been a Triumph fan, thanks to his training by racer and stuntman Bud Elkins. He's the guy who jumped over the fence in The Great Escape and crashed the bike that McQueen avoids during the Bullitt car chase. (Yes, he drove the Charger, too.) The filming of On Any Sunday exposed McQueen to the lighter, more nimble Huskies thanks to Malcolm Smith, an accomplished racer who had also converted to the brand. McQueen always had Huskies in his fleet from that point on.
This particular 250 Cross was one of them, purchased new by McQueen in 1971. It comes with all of the corresponding original documentation to prove that the bike originally belonged to McQueen. Its history between his ownership and now is less clear. At some point, the bike got a full restoration, but there are no records indicating who did this or when. It's still not quite in perfect condition, which shows that the bike has continued to be lightly used over the years. No doubt McQueen would approve of that.
You may not want to ding it up too much, though. The bike is expected to sell for between $50,000 and $60,000. That's a lot for an old Husky, but not many have the heritage that this one does.