In November 1943 Leonard volunteered to drop rank to Wing Commander and return to operational flying as Officer Commanding No. 617 Squadron – The Dambusters.

He continued to innovate and seek unconventional solutions to challenges, often by-passing established and official channels. He pioneered low level precision marking, seen here in this photograph taken from his aircraft showing the marking of an aero engine factory at Limoges. This enabled the accurate bombing of targets in occupied territory, minimising collateral damage to civilian homes and property.