Peter, you are obviously holding papers that most people would love to dribble over..., lol ! Especially those researching Thomas b1767. Perhaps the 3rd (King’s Own) Dragoons or the 4th (Queen’s Own) Dragoons or one of the Royal Cavalry regiments.
Reading your post, you are assuming that Richard is simply a relative, but with the parents and grandparents of Sarah and Thomas..., you have a Thomas / Sarah / Michael / Frances / William / Ann / ..., but there are no siblings or nephews called Richard !
Lol ! I had never imagined that there were “married quarters” during the Napoleonic battles ! (to have Richard born in a military establishment) So I suppose he was an officer.
(Thomas in the 41 census is down as a carpenter)