Complex sentence: Sumner was posted to No.142 Squadron RAF at RAF Binbrook in December 1940 and joined the crew of Wing Commander William Sadler and second pilot (known as'2nd Dickie') Pilot Officer George Bull.
Split into simpler sentences: Sumner was posted to No.142 Squadron RAF at RAF Binbrook in December 1940. The second pilot (known as'2nd Dickie') was Pilot Officer George Bull.