The only mural to be produced by Pablo Picasso in England is to become the centrepiece at a new London gallery.

The doodle of two angelic figures has been bought for £250,000 by the Wellcome Trust - the world's largest medical research charity - for its new Euston-based "cultural venue".

Measuring 8ft by 5ft, the impromptu artwork was drawn by Picasso during a drunken evening on the wall of a Bloomsbury flat owned by Irish physicist Professor John Desmond Bernal.

It was created in 1950 when the pair planned to attend the World Peace Congress in Sheffield.

The conference was cancelled and Professor Bernal organised a dinner party at his Torrington Square flat for some of the delegates stranded in London.

During the night he invited Picasso to draw on his living room wall.

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 wine, came together."

The mural was removed from the wall when the flat was demolished and Professor Bernal presented it to the Institute of Contemporary Arts in 1969.

It was loaned to the Clore Management Centre at Birkbeck College, where Professor Bernal worked.

It will go on display in June when the Trust opens the Wellcome Collection, a cultural centre dedicated to life and art in the context of health and well-being.