24 Apr 1835 Commissioned Staff Assistant Surgeon.
4 Aug 1835–30 Nov 1838 Served at Gibraltar and Malta.
June-Oct 1837 Epidemic of cholera in Malta.
Nov 1837 Served in Gozo and in the regimental hospital of 59th (2nd Nottinghamshire) Regiment of Foot, which was attacked by cholera.
Malta 30 Nov 1838 Returned to England.
10 Jan 1840 Promoted Assistant Surgeon 39th (Dorsetshire) Regiment, vice Assistant Surgeon Robert Martin Davis, who died at Madras on 10 Oct 1839. The vacancy created on the Staff by the promotion of Sinclair was filled by Gentleman Joseph Burke.
17 June 1842 Appointed Assistant Surgeon 13th Light Dragoons vice Assistant Surgeon John Clark who was promoted Staff Surgeon of the Second Class.
30 June 1843 Assistant Surgeon William Sall 95th Foot was appointed to the vacancy created by the death of Assistant Surgeon John Sinclair on 15 June. Consequently, Gentleman Edmonds Robert Richardson was commissioned Assistant Surgeon vice Sall.