Information on Graham Francis Clark (my father) please

I'm wanting to find out which regiment my father Graame Francis Clarkhame Francis Clark was in during WW2. I know he went from North Africa to Italy and was in Messina in Sicily on the 9th November 1944 ( as per what hes written on the back of a photo he sent to his mother) but I have no knowledge of when he signed up or what unit he was in. I believe he ended up at least a Lieutenant if not a Captain. My understanding is he was on landing craft. He did some training at Brockenhurst, Hampshire. He was born in 1923 so may have lied about his age when he signed up. He was told when he got promoted to grow a moustache so he looked older! He was known as Nobby Clark as most people with this surname were. I attach a photo of (I believe) the unit he trained with along with 2 other single ones. Any information would be gratefully received.