In reply to Tasered Baby:
You might look in Blacks' sale, as there were Marmot and Lowe Alpine offerings in Reading and Poole recently. Good reductions, too (e.g. £150-ish down to £60). Oh, and some Berghaus hydrodown jackets, too.
The Quechua one above is (obviously) at Decathlon:
http://www.decathlon.co.uk/for700-xxlight-men-down-jacket-id_8281847.html
It got the previous version (when it was in their Wed'ze skiing range), but the transfer to the Quechua brand seems to have been associated with either a real reduction in fill quality (90/10 to 85/10), or a more accurate reporting of the fill...
I've used it for skiing as an overlayer, and general use. It's definitely in the 'down midlayer for active use' category, though, not a belay jacket. It has a very lightweight shell so the whole thing weighs only 250g (medium). the design of the shoulder baffles is better than you see on many cheap jackets. And on some of the more expensive jackets...