What's a service history worth ??

[cejsmith]

I saw a tvr today that was in vey good nick, the guy that owns it s has a automotive engineering back ground and for the last 10 years done the regular servicing himself ( apart from specialist jobs like diff rebuild).

My worry is , for the last 10 years it has no documented history and it's ok that i have spoken to guy and I'm sure he is fine, when I come to sell it what will people say and how much it could effect the price?

So in effect in reality my question is what's worth more a great car with no history or a average car with full history, and what would people actually buy?