Thorp was transferred to Sir John Jervis' flagship in April 1796, where he was to sit the lieutenants' examination.
Thorp's seniority as lieutenant was 1 May 1796, at which time he would have been 18 years and 7 months old, having enlisted the aid of his sister Jane to obtain documents asserting that he was over 20 years old, the minimum age for candidates sitting the lieutenants' examination.