Yes here it is in black & white...
Metal detecting permit application
Metal detecting permit application - Service
We are currently looking into the metal detecting registration process and apologise for any inconvenience this may cause.
In the meantime, you are allowed to metal detect on Crown Estate foreshore, but must read our terms and conditions here before doing so.
The Crown Estate generally seeks to encourage access over, and responsible use of, the foreshore and as a result Crown Estate consent for non-commercial metal detecting on the foreshore will not incur a charge.
Seabed Metal Detecting
At present The Crown Estate does not grant permits for the sea bed as the Treasure Act does not apply below the foreshore.
Finds above the low water mark are generally the property of the landowner, unless classified as Treasure. Wreck on the seabed may still legally belong to a third party, therefore we recommend that any finds, particularly whilst you are diving or snorkelling, are not removed and are reported to English Heritage and the Receiver of Wreck.
https://www.thecrownestate.co.uk/rural-and-coastal/coastal/metal-detecting/metal-detecting-permit-application/terms-and-conditions/