Sir Paul McCartney was stranded in the French countryside for six hours after his Eurostar train broke down.
An overhead power cable snapped under the weight of five inches of snow, leaving Paul, his wife Nancy Shevell, 51, and daughter Stella, 40, stuck in the middle of nowhere.
But despite the ordeal, the 69-year-old former Beatles star - who was on his way back to London from Stella's Paris Fashion Week show - is said to have kept his cool.
A source said: ''It was a pretty hideous situation but Sir Paul was on fine form.
''He had a laugh and a joke as he chatted with the passengers in his cabin and he signed dozens of autographs.
''He was more than happy to muck in and try to keep everyone's spirits up despite the vile conditions. He's not prone to diva tantrums. He understands that these things can happen.''
The breakdown caused delays of 11 hours but Eurostar says the problem has now been fixed.
A spokesman told the Daily Mirror: ''The good news is we are not expecting any more problems with the power cable.
''We were doing everything we could to keep trains moving but it wasn't something in our control.''