Last Century, (always wanted to say that) I was the MS doing the accounts in my local cong.
I seem to remember that the PO said that EACH cong was a charity in it's own right. I'm assuming this is still the case. But it seems to me that the UK charity commission would wonder about this from a fairly small (overall) organization.
The paperwork from the commision was apparently quite onerous and if every cong in the UK had to fill it in and send it off to a deadline etc then the work for the Commision would be quite large for relativly small amounts. maybe their fed up with it all.