At the height of an uproarious party in his Bloomsbury flat one November night in 1950, Professor John Desmond Bernal, the scientist, asked his most distinguished guest to draw on the living-room wall.

Pablo Picasso climbed on to a stool and, fuelled with red wine and urged on by his fellow guests, improvised a pair of angelic figures. The only mural that the 20th century’s greatest artist produced in England was later to be chiselled out of the plaster and has now been acquired by the Wellcome Trust for its ambitious new gallery in Euston which will open on June 21.

Bernal’s Picasso is seen as the ideal emblem for the Wellcome Collection, a £30 million venue exploring the connections between medicine, life and art.

Bernal met Picasso in 1950 when they both planned to attend the World Peace Congress in Sheffield. The conference never took place and a number of delegates were stranded in London, including Picasso. Bernal organised a party in his flat in Torrington Square and it was there that Picasso drew the mural.

Ken Arnold, head of public programmes for the Wellcome Trust, said: “It is a rather wonderful emblem of an extraordinary moment in the history of art and science when these two great figures and quite a lot of red wine came together.

“Bernal asked Picasso if he could do a drawing on his living-room wall. As I understand it, Picasso stood on a stool and started to draw. Then Bernal and the others stood up and started urging him on and making suggestions.

“Picasso stood back from it, having drawn just a man with two horns. Then he broadened the mouth. Then he added a second face to it. When someone said that it should carry a message of peace, he added the wings and the wreaths.”

The mural was chiselled out of the wall when the flat was due to be demolished and Bernal presented it to the Institute of Contemporary Arts (ICA) in 1969.

It was displayed at the institute, which does not have a permamanent space for collections, and then went on loan to the Clore Management Centre at Birkbeck College, where it has remained since. The Wellcome Trust bought it for £250,000. The ICA and the Bernal family have each said that they always wanted the important piece of work to stay in the public domain. Ekow Eshun, the artistic director at the institute, said: “It was very important to the ICA that Bernal’s Picasso remained on public display. It is especially fitting that its new home is a centre dedicated to the relationship between art and science.

“I am sure that the mural will continue to inspire generations in the future as it has over past decades.”

Bernal’s Picasso will be on display at the Wellcome Collection from June 21. Access to the venue is free.

A man of affairs

— Professor Bernal, who died in 1971, was an eminent Irish physicist who worked on X-ray crystallography and took the first X-rays of hydrated protein crystals

— Known to his friends as “Sage” because of the breadth of his knowledge, he played a vital role in the D-Day preparations

— He advised Churchill and Roosevelt in 1943, designed floating harbours for landing supplies and selected target beaches

— He was given the temporary rank of commander in the Navy during the war, so he did not stand out as a civilian when he landed in Normandy

— A dedicated Marxist, he founded a forerunner of the Campaign for Nuclear Disarmament, and was a lifelong apologist for the Soviet Union

— Concerned by the power of nuclear weapons, Bernal was the first person to coin the phrase “weapons of mass destruction”

— He was a believer in free love whose prodigious sex life led Dina Fankuchen, his research partner’s wife, to start a “Society of Women who Have Not Been to Bed with Sage”. She was the president. The only other member, Bernal’s secretary, Anita Rimel, later had to leave the society

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