Hello Scrimnet,
no, I don't think it was them, unless they were imprisoned in Devonport.
It is not easy (or is it just me

) to find anything about the Naval Prison in Devonport. The prison is now known under the name Hangman's cell, as far as I know.
I got a few answers from several archives, so next week I will go to the library of Plymouth and dig around a bit. Meanwhile I also have a few request running for the archives of Kew, where a lot of military records are being kept.