In reply to damowilk:
I use a cheapish Voodoo hardtail from Halfords, which has been up and down many Scottish glens. It's good enough not to break down much, but not so fancy anybody would spend a lot of time trying to pinch it. I got one with mounting points for a rear pannier rack, which makes life much easier. You can bodge panniers on bikes without the lugs, but it's a pain.
A friend of mine takes the simple and cheap approach even further, using a 20+ year old Peugeot mtb with no suspension at all, and not much in the way of decent brakes, either. It would be horrible to ride at a trail centre, but for long approaches it does the job, and absolutely nobody would want to nick it.