David was born in November 1914 in Huddersfield, Yorkshire, eldest son of William and Winifred Crook. He was educated at The Leys School in Cambridge before entering the family business – Messrs. Benjamin Crook and Sons, Ltd, sporting goods manufacturers of Fitzwilliam Street, Huddersfield – of which he became a director. 

He was a member of the Huddersfield Old Boys Rugby Club, a keen skier with frequent trips to Switzerland, and a rock climber in both the Lake District and the Canadian Rockies.

Fascinated by aviation, he took private flying lessons at Ganton, near Scarborough, in 1934. In 1938 he joined the Auxiliary Air Force at Yeadon as a Pilot Officer. 

When war broke out, he was called up to serve full-time, completing operational flying training during the winter of 1939-40. 

On the day he was called up for service in 1939, David married Dorothy Margaret Middleton, eldest daughter of the Rev. Frank Middleton, English chaplain at Lausanne. 

In the spring of 1940, he rejoined 609 Squadron, flying with them during what came to be known as the Battle of Britain. His actions during the Battle were recognised by the award of the Distinguished Flying Cross (gazetted November 1940). The official notice of his award said he had “led his section with coolness and judgment against the enemy on many occasions. He has destroyed six of their aircraft besides damaging several more."

In November 1940 he was sent on the Instructor’s Course at the Central Flying School, serving as an instructor after that at AFUs (advanced flying units) and OTUs (operational training units). In late 1944 he was at No.8 (Coastal) OTU at RAF Dyce. On 18 December he was on a high-level photographic sortie. His Spitfire was seen to dive into the sea near Aberdeen. His body was never recovered. He is remembered by name on CWGC’s Runnymede Memorial. 

David was 30 years old. He and Dorothy had three young children, Nicolas, Rosemary and Elizabeth.