He is credited with the idea of the Jamaica International Exhibition of 1891 but died on its opening day.
He was also the joint compiler with Laurence R. Fyfe of the Colonial Secretary's Office, of the first editions of the long-running Handbook of Jamaica, from 1881.
[4] In 1889, Sinclair and Fyfe produced a history of Jamaica during the governorship of Sir Henry Wylie Norman (1883–89) which, typically of their historical works, concentrated on chronology and fact-based material rather than analysis.
[5] For many years he was unable to drum up sufficient support for his project for a Jamaican equivalent, but in 1889 Sir Henry Blake arrived as the new governor of Jamaica and gave the idea his blessing.
[5] Sinclair died, aged 58, at 106 King Street, Kingston, on 27 January 1891, on the day of the opening of the Jamaica International Exhibition.