Cheers Martin,that would be great in rain and I'd be getting a cover for it too. There's no need to pay a fortune either,I've just seen a page of them in my photo mag. and tbh. the transparent plastic ones will do the job just as well as the expensive ones - I think
and you can see what you're doing too.Anyway here's the link.You even get two for £5.75. they're called Optech rain sleeves. Fits lenses up to 17.8 cm. long (7 inches in old money). and 47 cms (18 ") width .The photo shows it on one of Canon's white lenses on a camera - looks like a 70-200 or maybe a prime 300/400mm.
Here they are at Warehouse Express for 20p.more
http://www.warehouseexpress.com/buy-OpTech-Rainsleeve/p1017072?utm_source=google&utm_medium=cpc&utm_term=optech%20rainsleeve&utm_campaign=F%20Bags%20/%20Rain%20Covers&cm_mmc=google%20Warehouse%20Express%20-%20Bags%20%26%20Tripods-_-F%20Bags%20/%20Rain%20Covers-_-Optech%20Optech%20Rainsleeve-_-optech%20rainsleeveHere's a good photo but £2 more at Amazon
http://www.amazon.co.uk/Tech-Rainsleeve-Digital-Cameras-Lenses/dp/B000PTFDYOI googled Newpro.co.uk which is the contact given by the magazine but they seem to be showing other companies so I googled the sleeve name Optech. You need one anyway for your rough seas photos that you get now and then - keep that salt spray off the gear.