In early 1881, owing to continued ill-health, he rejoined Sir Arthur Gordon, who had gone to New Zealand as governor, but in March he was appointed deputy-commissioner for the Western Pacific, and started for his first long tour through these seas in H.M.S.
After a visit on sick leave to England, succeeded by a short stay in Fiji, he was ordered to New Guinea for the first time, at the end of 1883.
On 17 Jan. 1887 he once again started for the Pacific, staying en route in Egypt and Australia, and in June took up the appointment of deputy-commissioner and consul of the New Hebrides and Solomon Islands, residing chiefly at Port Moresby, New Guinea.
There was a good deal of native hostility, and he was much isolated, owing largely, he believed, to the neglect of the home authorities.
While there he contracted fever, and, returning home, died at Cecil Street, Strand, London, on 27 July 1892.
Romilly is described by Arthur Hamilton-Gordon, 1st Baron Stanmore as of "a quick intelligence, great physical strength, and an easy temper."