Local practices might also be relevant. In most of the country if a property is put on the market at £325k, an optimistic buyer might try an offer of £290k, which is a discount of a bit more than 10% of the advertised price. However if the vendor is in no hurry to sell, they might eventually get an offer of perhaps £315k.
In areas such as Sheffield though, the advertised price is simply a base price which people are expected to bid quite a bit above, with the estate agent possibly expecting to see a bid from an optimistic purchaser of £330k but expecting to actually sell the property at closer to £350k.
(When the Manpower Services Commission moved their HQ from London to Sheffield there were lots of Londoners looking to relocate to Sheffield. Many of them ending up writing letters of complaint to the local newspaper, protesting that even though they'd offered the full asking price on several properties, they'd always had their offers turned down. They couldn't understand the Sheffield way of doing things, whereby the very lowest offer submitted for a property is often 10% or more higher than the advertised price!)