a very well-produced image Mike!
here comes the bad news, sadly there is no way that this could be identified from a macro shot - it would need microscopic examination and possibly culturing . . .
by no means even could one say it is a 'pin mould' in the restricted sense, i.e. a member of the Zygomycota
I am about to revive the
Fungal Plant Parasites thread as there is so much interesting (and identifiable - even to the beginner) stuff around at the moment (I added a rust fungus to the Yorkshire list only yesterday

- no mean feat, trust me) and would welcome samples of things people find -
but NOT your tomato please

cheers
Chris