Did the British officer fight for the British?
Was it Władysław Franciszek Jabłonowski? (The house would have been a barracks at Brienne....)
Wellington born in Dublin
Study in Eton, then Brussels, then " Art of Cavalry" in Angers
Hudson Lowe certainly met Napoleon.... Perhaps he stayed in the same house as the man when he was traveling through Corsica in the 1790s or when he took part in Tuolon.
I must say, this is one of the harder ones you have posted (I think the hardest was the Algeria one). I do enjoy these- it forces me to look into some really interesting things.
Rgds,
Sandor