Rapha, nice but a bit pricey?

if you don't want to spend for a waterproof bag get a dry bag or something similar to put in your existing one. Lomo 35L diving drybags are £6.50 each!

http://www.ewetsuits.com/acatalog/Dry-Boxes-dry-bags-uk.html

Thanks, will invest in one of these. Went over to Bike14 at lunch and whilst the Mission bags look great they are £200. Don't think i can quite justify this to myself yet...