Goodwin paid $250,000 (£190,000/€222,000) for the seat in 2005 but feared his Parkinson's diagnosis would mean he could not take part.

The 80-year-old represented Britain in canoeing at the Munich 1972 Olympic Games.

"From becoming an Olympian to canoeing between the peaks of Annapurna, to winning a six-day race in the Arctic Circle and climbing Mount Kilimanjaro, I've always enjoyed rising to new challenges," Goodwin said.

"When I was diagnosed with Parkinson's in 2014, I was determined not to let it stand in the way of me living life to the fullest.

"And now for me to go to space with Parkinson's is completely magical.

"I hope this inspires all others facing adversity and shows them that challenges don't have to inhibit them or stop them from pursuing their dreams." 

The tickets are now worth as much as £350,000 ($456,000/€406,000) but to Goodwin it is invaluable.

"I think the opportunity to do something that's not been done before by many people at that price is a real bargain," he said.

VSS Unity is also due to carry mother and daughter Keisha Schahaff and Anastatia Mayers who won their seats in a draw that raised funds for non-profit organisation Space for Humanity.

They will be led by Chief Astronaut Instructor Beth Moses who was the first woman to fly to space aboard a commercial space vehicle.

"This flight highlights two of Virgin Galactic's core aspirations – increasing access to space and inspiring people around the world," said Virgin Galactic chief executive.

"Each of these astronauts are role models and beacons of inspiration in their communities.

"Watching Keisha, Ana and Jon embark on this transformative experience helps demonstrate that space is now opening to a broader and more diverse population across the globe."