Oh I say. Thank you very much. It seems to be the common spangle
gall, with some of Mr. Harvey's smooth spangle gall, which I
mistook for "immature galls". Fascinating stuff, there's some
information at:

http://www.btinternet.com/~arb_excha...d_spangle.html

with a link to the "currant galls" which are part of the life-cycle
of the wasp earlier in the year.

Concise information and well worth a glance!

Thanks again.