 Soon after arriving in Hong Kong, in April 1877, Hennessy set out to implement the "separate system" in Victoria Gaol, meaning separate cells for prisoners, during the night if not also during the day.This plan hinged upon sending long-term prisoners to Labuan, for convict labour.After his tenure as Governor of Hong Kong was over, Hennessy went on to become the 15th Governor of Mauritius from 1 June 1883 to 11 December 1889.