We too think that Samuel was in the forces. We have found records of Samuel in the Maltese Census for 1852 (Royal Naval Hospital, Bighi) and 1860 (Ospedale Navale, Vittoriosa). These records were on the Maltese Family History site, have you tried there? (http://website.lineone.net/~stephaniebidmead/second.htm
Samuel's brother (Silas) lived in Devon and George lived there with Silas' son whilst he was at school in UK. There are lots of Winters in that area!
Still no luck for me in finding further information though. Am hoping to go to Malta in the next 12 months so will let you know if I find anything. Good luck in your search too.