Some campaigners want to see Concorde fly again

In 1974, Prime Minister Harold Wilson told his French counterpart, Jacques Chirac, that his Cabinet was reconsidering the Anglo-French project.

It was estimated the supersonic jets would cost more than �1bn to develop, and British Airways �26m a year to fly.

The documents detailing the debate have just been released to the National Archives under the 30-year rule.

The jets eventually began commercial service in January 1976 and were retired from service in October 2003.

In my judgment... the cancellation of Concorde would have a much more serious adverse effect in the public mind than is now believed Tony Benn MP

According to notes of a conversation between the two Prime Ministers, Mr Wilson said: "It was the collective view of British ministers that continuation of the project could not be justified on economic grounds."

He went on to say that, although no decision was made, "if it had to be taken tomorrow, it would be a negative one on economic grounds".

In a separate letter, Chancellor Denis Healey came out even more strongly against Concorde.

"It seems clear to me that the right course is to aim for cancellation of the project.

"If it were impossible to achieve without French agreement except at the risk of excessive compensation, we should stop at the end of the 16 aircraft programme," he wrote.

But the project had the backing of the Bristol MP, Tony Benn, then Secretary of State for Industry.

"In my judgment - and I have to make allowances for my close constituency interest in this aircraft - the cancellation of Concorde would have a much more serious adverse effect in the public mind than is now believed," he said in a letter.

Mr Benn was also worried about the impact cancellation would have on industrial relations in areas - including his own Bristol South East constituency.