Sutherland portrait of Churchill displayed for first time in 20 years

A portrait of Sir Winston Churchill, painted by Graham Sutherland in preparation for a later work destroyed by the wartime prime minister's wife, is to go on public display for the first time in 20 years.

The painting has been lent by a private collector to an exhibition of 120 works by Sutherland – his first important show since a retrospective in 1982. It was produced in the 1950s as a preparatory work for a painting commissioned by the Houses of Parliament to mark Churchill's 80th birthday.

The final portrait was to have been kept by Churchill for his lifetime and then hung at Westminster. But he was uneasy at what he described as the "force and candour" of Sutherland's work. The final painting was destroyed by Lady Churchill in what the artist said was an act of vandalism. The preparatory painting is regarded as Churchill's finest surviving portrait.

The exhibition runs from 25 February to 2 March at the Fine Arts and Antiques Fair at Olympia in London.