If that photo is of an F.1, then it isn't a sonobuoy aerial, as the F.1 didn't use sonobuoys. I have searched through the AP but find no mention of it, but I think it may be the early position for the IFF aerial.
I don't have my references with me at this time, but I had checked them before I left. As I recall, this squadron was part of a group that did BoB patrols during early 1945, from the airfield where this squadron was based.
Looks great. One thing with this one (Isn't there ALWAYS one thing...! ) is that it had the single colour uppers - EDSG only - by this stage of the war.