It isn't known for certain how many 1956 Fazakerly No.4 Mk.2's were made, but the numbering suggests to me that that could be thousands.
If so, I don't know where they are. I have UF 56 A434xx, and I know of two others in Canada. Skennerton
has an illustration of a No.4 with a UF 56 serial number. I like to think they're still out there somewhere, in the wrap.
In a thread on CGN, another fellow has suggested there's an even later run, with letters UP
I'd like to know more about this too. It's a little vague when you get to the 56's.