Dusting off my lapsed RICS membership and Chartered Surveyor's hat...

Mortgage valuations rarely match sales prices but that doesn't necessarily mean a mortgage wont be approved, the lender will consider a number of other factors.

Your friend should also be able to tell you how crudely valuation methods are applied to domestic properties. Very rarely does they stray outside of the Comparison Method and within that method there is very little stringency applied in assessing how similar properties really are; the most important factors being general things such as numbers/sizes of rooms etc, general location and the most recent sales prices. So the Bovill Road price has a very real chance of affecting the price at which other properties in the area are marketed.