Surveyors Valuation

What credence do you give to a surveyors valuation vs bank valuation?

Property listed at £1.425 mil, offer accepted at £1.4mil. Bank valuation was £1.4mil, however surveyor on our Rics Level 3 has said it is only worth £1.25mil and is citing stagnant market etc.

Do you think this is grounds for a renegotiation on price?