The rocker was due to take to the stage at Britain's Glastonbury festival with his The Who bandmates in 2007 but was left feeling extra nervous after seeing Bassey steal the show with her set earlier on the bill.
Townshend joked to a pal that he hoped the chopper Bassey was using to ferry her to and from the site would crash, but he regretted his words hours later after discovering the aircraft had been forced to make an emergency landing after suffering a mechanical failure.
The guitarist tells The Times, "Our challenge was a strange one: Shirley Bassey. She went on before us and did a storming set, full of humour and irreverence - at the age of 70 she went down on her knees and got back up again, which I tried and failed to do - and it was like we were following Elvis.
"When she came off someone said to me: 'Good luck following that'. And I replied - joking, I should add - 'I hope her helicopter crashes.' And it did! She... had to make a landing in a field."
Bassey and five others on board the helicopter escaped the incident unscathed.