In reply to sam.sam.sam.ferguson:
£36 for a pair of cotton jogging trousers? Obscene!
The decathlon ones he's referring to can't be found without a direct link (
http://www.decathlon.co.uk/mountaineering-trousers-id_8010075.html ), but they are winter softshell mountaineering trousers (pretty good also) and so not suitable for doing much anywhere else as you'll be proper fookin hot like.
OP; If you must have a pair of hardwearing climbing trousers - I assume this is for spring and autumn outdoor trad climbing? (in the summer I can't see why you wouldn't be in shorts). I would suggest a pair of trackie bottoms that you already have. If you MUST buy something:
Montane's "Terra" trousers are pretty solidly great for a (VERY) hardwearing trouser. Super lightweight but not stretchy (unless you get a certain version). (ebay specials here!)
Rab's "Vapour Rise" trousers are like a lightweight windproof, weatherproof and slightly insulated version of what you'd think of as a classic tracksuit bottom, I love them for cold days outdoors with a t-shirt and a warm jacket for post/preclimb. (available on ebay all the time)
Decathlon do a similar to montane's terra pant (
http://www.decathlon.co.uk/forclaz-900-regular-trousers-id_8171845.html ), that is hardwearing and stretchy and wicking but not waterproof. These look pretty good (and do come in colours other than red. There's a slightly stretchier and more comfortable version with a water repellant coating for a bit more (
http://www.decathlon.co.uk/bionnassay-900-trousers-id_8225063.html ).
Those should be the kinda thing you're after.
Note I wouldn't like to run in particularly any of these apart from the vapour rises, and then even in the snow running in trousers is pretty toasty.