Cheap XC - How does this look?

[Accelebrate]

I want an XC bike, I used to do quite a lot of off road cycling when I was younger and I'm missing it a bit. I do a lot of cycling at the moment but it's all road based, mainly for commuting, so it'd be quite nice to have a spare bike so that repairs can wait until the weekend. I cycled everyday whilst it was snowing last winter and I intend to do the same this year, so an XC bike might come in quite handy as it was a bit interesting on 700c slicks.

So that's it justified, but the reality is it'll only see light use, I've got a house renovation project on the go at the moment so the majority of my spare time is accounted for. So something cheap makes sense, but I've owned nicer bikes in the past so the really bargain basement stuff doesn't really appeal. Secondhand looks like a sensible option, I'm not really fussed about it being new, to be honest I'd almost prefer it not to be.

Would this be a poor way to spend £250? It's only around the corner so scores well on the lack of hassle scale...

http://oxford.gumtree.com/oxford/98/67030798.html

How can I ask the seller to prove it's not stolen without him taking offence?

[Accelebrate]

That is my only concern. Bike theft is far from uncommon around here.

[Accelebrate]

Hmm, well I sent the seller a message asking a few general questions and if he could provide any proof of purchase earlier today. He has since added the bike to other classified sites locally but not replied to my message, so I guess that sort of answers that.