In 1979, Sir David presented Life on Earth, a landmark television programme made in Bristol, which attracted around 15 million viewers.

“Bristol led the world to be truthful,” he said.

“It started this with radio, and when television came along, Peter Scott and Desmond Hawkins continued that tradition.

“The other big mega power in broadcasting was the United States, and in the 1970s, viewers there thought natural history was just lions attacking antelopes.

“Bristol’s programmes taught them that termites could be just as interesting.

“When we first started trying to get the subscriptions to finance the plans I had, I remember making the mistake in pitching this to an American network controller.

“I waxed very eloquently about how the programme would be the history of life from the microscopic beginning, and the executive turned to me and said ‘you mean it’s going to be about green slime?’

“I replied ‘more or less,’ but we managed to flog it in the end.”