Cobs are brilliant!! Especially if you are nervous. I dont think age matters aslong as you are prepared to take on the task of "if he does get a bit skittish" But you may find if and when he does that you will know him and have to confidence to tell him off if naughty and point him in the right derection!

Good Luck

I bought a horse once who was only 4. He was the most sensible, sane horse I've ever had. I rode him for a couple of months and then turned him away to mature a bit. When I brought him back into work, I took the tack to the field, tacked him up in the pouring rain and rode him back to the yard. He didn't bat an eyelid. One day I decided to break him to harness and because he was who he was, didn't bother with the preliminaries - just attached him to the cart (I'm not recommending this by the way - I was young and didn't know any better). He did wonder for a few minutes what was behind him but I told him it was OK and off we went. Just in a straight line, up the lane but again, he accepted it all in great good humour. We actually used to use him as a cover horse when we were riding just-backed babies out for the first time. He was just born bombproof.

Same with another horse, again a four year old. Had it in to break and sell on. Stunning Arab-y skewbald. If you didn't know better, you'd have thought he was 12. Just took everything in his stride.

IME, if they're sensible at 4 they tend to stay sensible; they might go through a slightly livelier stage at some point but still have that nice, reassuring core of sensible-ness