Personalities stamps

Does anybody know who puts out the 'Personalities' Stamps, please? We found one of their series and the box needs a little tlc. We haven't removed it as the stamp is still fine. Any help? Thanks.

As we understand, they are the property of a boxer called 'Captain E' a Plymouth person. He/she plants them in batches of 6 -10 and circulates the clues to a very few selected friends, then eventualy after 6 - 8 months the clues are published in the Dartmoor Updates.
The owner never maintains these boxes. not even after the clues have been deleted from the Catalogue under the 5 year re registering rule.

If that's the case it's a real shame as there is a load of history in the book and the stamp must have taken a few hours to carve