ekinsdc, welcome to PPRuNe, the Military Forum, and in particular this very select thread. I hope that the varied and informed knowledge and experience crammed into our cyberspace crew room can come up with some answers for you and maybe even pics of your father.
In the meantime the picture that you posted seems to raise more questions than answers itself. If A2-2 was flown and recovered to HMAS Sidney off Lee-on-Solent, what is it doing off it again in Portsmouth Harbour? The Seagull V itself seems to be perched rather precariously above the side of a ship (HMAS Australia?), or dangling from it, or what?
Please excuse the lack of Naval terminology, but we do have such expertise to hand who will no doubt severely take me to task. At least I didn't call them boats, though I suppose the aircraft is a flying one albeit amphibian. It appears to be anyway!
https://www.flickr.com/photos/41311545@N05/5935474118/