Number 23 ITW AIR 29/634 Stormy Down

Hi All
First post, fingers crossed, I'm trying to trace my friends dads WW2 history, he is 94 and still going strong, sadly doesn't remember all the details but what he has said I will put here, the fact he was a coastal command navigator on mosquitos really excited me
He started the war fighting for the French Army in North Africa and then accepted the call from De Gaulle to come to the uk to fight. I believe his first base was Stormy Down, possibly number 23 ITW, from there to Canada, possibly Quebec, back to the UK but he can't remember squadron numbers but finished the war as a Nav on Mosquitos. Sadly no log book and has said he is the last one left, lives in the South of France his name Alain de Bengy ( de ) puyvallee 21 August 1921.
Any help or direction most appreciated, am an ex fleet air arm mechanic but please don't hold that against me