Complex sentence: On 3 April 1941 he joined No.92 Squadron RAF based at Biggin Hill where he flew the Spitfire and on 4 September 1941 he claimed his first probable kill of a Me109 during an escort mission of Blenheim bombers.
Split into simpler sentences: On 3 April 1941 he joined No.92 Squadron RAF based at Biggin Hill where he flew the Spitfire. On 4 September 1941 he claimed his first probable kill of a Me109 during an escort mission of Blenheim bombers.