Robert Sadler was born in Newmarket, Suffolk, the son of a racehorse trainer. By the age of fourteen he was drawing and painting aeroplanes, horses, houses and landscapes. After studying at Eastbourne College and Sidney Sussex College, Cambridge he joined the Royal Air Force in 1930 as a pilot from Cambridge University Air Squadron.

In 1942, whilst posted to the Air Ministry as ‘Director of Plans’, he attended art school in London and spent the following year in Turkey on special duties where he lectured at the Turkish Air Staff College and painted and rode race horses. At the end of the war he returned to the UK and took up the post of Station Commander at RAF Binbrook in Lincolnshire. In 1947 he moved to Denmark as Air Attache to the British Embassy in Copenhagen where he attended art school and two years later, whilst Vice-President of the RAF Officers’ Selection Board, set-up a studio in Stockbridge whilst attending art school in Winchester. In 1953 he moved to the USA to take up the post as representative on the NATO Joint Chiefs of Staff Intelligence Committee during which period he attended the Corcoran School of Art in Washington DC where he first encountered the work of the American Abstract Expressionists. Returning to the U.K. in 1955 he moved back to Newmarket, having retired from the RAF ‘to devote the rest of my life to painting’. He attended Heatherley’s School of Fine Art in London, Cambridge Technical College and became a member of the Winchester Art Society and the Cambridge Society of Painters & Sculptors.