I think he got a "pension for three lives" after the Battle of the Nile i.e. it would be paid to him and the next two hereditary holders of the title so that they would be able to set themselves up in a situation in life in accordance with the dignity of the peerage (or some such feudalistic nonsense).
IIRC Pitt the Elder got one, as did Wellington.
Edited to add, Googling finally confirms this, see:
Rabbie, I wish to invite you to dinner and listen to you hold forth (not some drunken Cider filled bash). You really are a mine of information. The Professor is an ignorant boor in comparison...(dont tell him I said that).