After the first handstamp recorded for Crewkerne (“CROOK / HORNE”, in the 1990 edition of the British County Catalogue as “CROOK / HORN”, known in use from 1733 to 1783) are three handstamps in the BCC, all “CREWK / ERN” rarity Z, only known in archives.
SO 379 “CREWK / ERN”, 29x12mm, used in 1740, rarity Z
SO 382 “CREWK / ERN”, 27x13mm, used in 1740, rarity Z
SO 385 “CREWK / ERN”, 26x12mm, used 1759-1761, rarity Z
I've recently acquired an entire dated 23rd June 1766 which has a faint “CREWK / ERN” handstamp on the reverse. I've measured it at 27x13mm so it could match SO 382, the middle of the three above.
I'd really like to check the handstamp with the one identified in the British County Catalogue - when the lockdown is over I'm planning on visiting the Somerset Records Office to see if that is where the Crewkerne "found in archives" handstamps come from.