Thanks to a bit of synchronicity I just found this statement from the Inland Revenue:
The present regulations were laid on 24 March [2005]. These make changes to the CTF regulations to allow credit unions to offer their cash deposit accounts for the CTF.
I think this is good news and could well be the best place to put those pesky government cheques — get them invested in your local community. Sure, cash deposit is low return, but also low risk. Doesn’t seem to have been much publicity about this, perhaps unsurprisingly. Well, you know now. Spread the word!