Complex sentence: In January 1942 he joined No.72 Squadron RAF flying Supermarine Spitfire's from RAF Biggin Hill carrying out operational fighter sweeps and bomber escort missions over the English Channel occupied France and the Netherlands.
Split into simpler sentences: In January 1942 he joined No.72 Squadron RAF at RAF Biggin Hill flying operationally. He flew on fighter sweep and bomber escort missions over the English Channel occupied France and the Netherlands.