Ok so it's not a boot per say. However it might as well be.
Bloody brilliant.
I had been using an old pair of ankle Sealskinz socks which were ok.
However yesterday these bad boys arrived.
http://www.chainreactioncycles.com/s.../rp-prod152624
Wore this morning, ok so it wasn't raining - I don't doubt the waterproofness of them. But nice and toasty. Best £34.99 I've spent in awhile.