(British) Army List - for 1806
Page 44 notes George J-- Reeves(sic) as a General and Field Office in the Army with a rank of Major. He was appointed Major on 10 October 1805 and is serving with 27th Regiment of Foot. He has seniority of 652 (in a list of 673, so he's very junior, not surprising since he's only recently been promoted Major).
Page 164 notes George J-- (sic) Reeves as a Major in the 27th (or Inniskilling) Regiment of Foot. This confirms his Regimental Rank as Major and appointment. date of 10 October 1805.