I'd advise being a bit more forceful in your mission to purchase Tim.
Ask the vendor for a totally accurate description, "warts and all". A dealer will always be as honest as possible in my experience.
Based upon the description, decide whether you think the car is right for you and make an appointment to view at your earliest opportunity.
Offer a refundable holding deposit of say £250 to show good faith so that you have first refusal.
I did this just a fortnight ago on my IS250C. My old car was for sale on eBay and a guy contacted me over the weekend arrange to see it on the Tuesday, with a view to driving away on the day if he wanted it.
I was confident I had described my vehicle accurately so expected a sale. I contacted the dealer with the 250C on the Monday morning and after discussing condition etc. he accepted a holding deposit from me. On the Tuesday lunchtime, after a successful sale, I was able to agree a purchase in principle based on description. I travelled on the Friday to view and finalise the deal. Even at that point I was able to walk away with my deposit refunded if I didn't like the car.
My previous four car purchases have been concluded in a similar fashion. It's about trust and asking very relevant questions of the seller. Don't see why similar circumstances can exist with a private seller.
It's all about achieving first refusal status for yourself. Good luck and let us know what you get please.