Query about military ranks
 

In the 1820s, would an ensign in an English foot regiment be entitled to call himself a lieutenant?

I'm just trying to work out if I have two people with the same name, or one person.

Ensign would have been below Lieutenant, but apparently it was the equivalent of Second Lieutenant.
http://en.wikipedia.org/wiki/Ensign_...United_Kingdom

Yes, I'd seen that, thanks; I was puzzled by the bit where it says:

I'm almost sure that my ensign and lieutenant are the same person, but it isn't clear to me from that quote whether the names ensign and 2nd lieutenant would have been interchangeable in the 1820s.

This particular man was an ensign according to his service record (and never seems to have been promoted above that rank), but called himself a lieutenant when children 1 and 3 were baptised. He was already on half-pay by then, and called himself a farmer when child 2 was baptised.