There are stories that some miners were used as "sappers" / tunnelling etc.
i.e.
The current free miners owe their rights to their fore fathers of the 14th century, who won a battle for King Edward 1st by tunnelling under castle fortifications at Berwick Upon Tweed. ( It must have been well
remembered as the Northumbrian miners did the same to Newcastle City Walls in the Civil War). By way of reward King Edward passed a new law, giving the Dean miners the right to own their own workings. Broadly, any man who was born within The Forest Of dean was 21 or over and had
worked down a local coal mine for one year and a day was entitled to mine for coal anywhere in that location "without tax or hindrance".
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Ἀριστοτέλης A Gloster & Hereford Boy in the Forest of Dean ><((((*>