In reply to higherclimbingwales:
My one's don't have the model number written on them but they look closer to these ones;
http://www.amazon.co.uk/Cobra-MT600-Walkie-Talkie-Radio/dp/B000SA93L4/ref=p...
They appear to have risen in price quite significantly though! I bought them thinking I'd wreck them within a few trips but they have turned out to be fairly sturdy (I don't bother with a case or anything, just shove them in my hardshell chest pocket). My only gripe is the 'lock' button only locks the channel changers not the volume, thus you can accidentally knock the volume down to one in your pocket.
They were worth it for 20-30 but I reckon for 50 you could get something a little better. Maybe check out the motorola ones? I've only ever used the aforementioned cobra ones but have heard of others liking motorola radios.
If buying something more expensive it may be worth fashioning some sort of lanyard so you don't drop 40 quid of radio down a crag!