[1][2] He continued to serve in the company's administration of the protectorate, becoming successively a police magistrate and justice of the peace for Labuan and a District Officer.

He was involved in the suppression of the Mat Salleh Rebellion from 1895 to 1897 and was awarded The British North Borneo Company's Medal and clasp.

[2][3] After eight years service Applin had reached the rank of Captain Superintendent in the British North Borneo Armed Constabulary, but was forced to resign due to ill health and returned to England.

[5][6] In April 1902 he was granted the local rank of captain in the Army whilst serving with a provisional battalion,[7] and the following August he transferred to the Royal Garrison Regiment.

[16] In November 1916 he was appointed temporary lieutenant-colonel, and commanded the machine guns of the II ANZAC Corps at the battles of Messines and Passchendaele.

[2] With the entry of the United States into the war, Applin was part of a British mission to the country, and gave lectures on machine gun tactics.

Applin stood as the candidate of Anti-Waste League, a right-wing party formed by Lord Rothermere in opposition to the spending plans of the Lloyd George Coalition government.

Such was the unpopularity of the government that all three candidates, including the winner Brigadier-General John Nicholson of the Conservative Party (who formed part of the coalition), claimed to be "anti-waste".

Applin was the Conservative and National Government candidate, and was returned to the Commons when he defeated his Labour opponent by the large majority of 10,886 votes.