No official statement on metal detecting was found. A forum user says the council allows beach detecting with seasonal limits for birds, but this could not be checked against a council source. WWII ordnance has been found on Seaton Carew beach (news report).
We couldn't find a published rule. Foreshore owned by the Crown Estate follows the Crown Estate's terms; for council-owned beaches, ask the council before you dig.
Tap any spot in England on the UK Detector map to check it against scheduled monuments, SSSIs, nature reserves, National Trust land and access land in one go. Free: 3 checks a day.