Thanks for the replies!
I have just downloaded some ADM records from TNA confirming that our man was indeed a 1st Lieutenant in Royal Marines in 1835 when he is applying for his son's entry into the Greenwich Hospital School!
He was then (1835) living(/based?) in Dunkerque, France, and had joined the Plymouth Division of Marines on 2nd May 1804, and served on L'Africaine, Phoenix, Hibernia, and Minotaur. Unfortunately no dates for this ship service, but I'm a lot clearer on my man now!
Can't seem to find any records of service for him at TNA… any other ideas??
On one of the required records being sent to James, someone (a friend it would seem) has written "… I would have wished to have heard how you liked Belgium..'. So there's another line of interest!
Thanks so much for your imput!
Clare