I wouldn't personally put that much faith in the listing. My old house used to be in PR5 and was split into PR25 and PR26. Neither of these post codes are mentioned so the list is at least 15 years old. May well be very out of date, as I imagine that they would reasses the areas on a regular basis.
Also this is only 1 factor in deciding your risk category and many other things have a bigger effect.
Also this is only 1 factor in deciding your risk category and many other things have a bigger effect.