World Environment Day saw science experts celebrate the 20th anniversary of a time capsule that was buried at Kew Gardens.

Lord Robert May, former president of the Royal Society and chief scientific adviser to the Government, joined emeritus Professor John Guillebaud and others on June 5 to celebrate the time capsule project.

Professor Guillebaud, who buried the time capsule in 1994 as an address to future generations, said the project was an apology to people of 2044.

Sir David Attenborough, unable to attend due to a wildlife filming commitment in Spain, said: "I agree very much with your central concept that many of the world’s most grievous afflictions can be attributed to population growth: the unprecedented increase in numbers of one species - humans - whose environmental impact threatens the habitats and the very existence of nearly all others, in both the animal and vegetable kingdoms."