Hello Annie
His service record just says "CM 14.1.04 - to be imprisoned with HL for 12 months & dismissed HM Service." The CM was held on board theConqueror at Devonport although my GGF, Able Seaman John Henry Tyson was serving at the time on the Magnificent where the offence took place. I think there was/is a prison in Plymouth, which would have been nearest, but don't know if the Navy used specific prisons.
Regards
Leigh