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Ill have a go with a die-grinder and polish pot.
Sounds like the case of a very rare, IIRC, 1933 penny. In the 60s there was a chap who removed the last digit from some other 30s pennies and grafted a 3 onto them, his work was so good he fooled 3 dealers. He was caught because he sold 3 of them on the same day in the same town. It all came to light when dealer A called dealer B and said that he'd just manged to buy a rare 33 penny, dealer B replied me too, they contacted dealer C who confirmed that he had just bought one.
Again, if IIRC it was in Blackpool.