Thank you the OP is appreciative, of all help as he had already wasted money on shite sitesFrom a quick Google, there's an excellent personal account from 144 RAC here: 144th Regiment Royal Armoured Corps D-Day June 1944 operation Overloard
According to this, after 25th July 144 RAC were in defensive positions at Grentheville (SE of Caen and on the battlefield of Operation GOODWOOD. which had taken place there during the previous week) and the regiment suffered some casualties from intermittent shelling. I imagine that one of these casualties was him.
Believe it or not, despite the legends of Sherman tanks being 'Tommy-cookers' for unfortunate crewmen, the big killer of Allied tank crews in Normandy was random shelling/mortaring of their harbour positions, catching them unawares and outside of their armour.