Considering a full HPI check if £10, they're ripping you off to an amazing extent.

First question I'd be asking is this "Do I want to be doing business with a company like that ?"

IMHO it comes down to the total cost to change. I don't give a monkeys how the dealer build that figure but providing the car is what I want and the price is good (i.e. less than elsewhere) does it matter if you are paying a spurious £150.

By all means try and get it removed (or reduced but if walking away means paying more elsewhere surely that is just plain daft. Last time I bought a car form a supermarket it was 5 days old, brand spanking new basically and had been prepped by the supplying dealer before it even went to a supermarket. They wanted a £50 valetting fee which was probably need on some of the grubby ex hire stuff on site but not on a new motor. To get the deal they removed it but I would still have bought it anyway, it was £3000 less than a grubby year old one from the local Ford emporium.

Response from dealer: "The indemnity insurance is to protect you to make sure that the history of the vehicle is guaranteed for as long you keep the car." I thought the dealer had to guarantee the history of the vehicle, and any discrepancy I uncover would protect him if I sue. Isn't guaranteeing the history all part & parcel of the "attraction" of buying from a dealer?