Bagged one of these (the black/reds are the cheapest)a couple of week's ago when they were a tenner cheaper still (pricing error?).

http://www.wiggle.co.uk/omm-aether-smock-1/

Not cheap, but still a hefty discount and the smock is as light weight as the old Montane H2O it's now replacing. I've only worn it twice over the last weekend's deluge and seems okay - time will tell!