The plan was for all British merchant ships in Aden harbour to be taken up from trade and sent to Perim with large gangs of Arab coolies aboard. These would load up as much coal as they could and return to Aden. If time permitted ships would return to Perim for another load. In the meantime the coolie gangs of the Perim Coal Company, working under the orders of the Assistant Resident there, would jettison as much coal as possible into about two to three fathoms of water. Any stacks of coal not thus recovered or jettisoned would have to be fired. It was estimated that 500 coolies would take five days to jettison 10,000 tons of coal into Perim harbour. Since the 300 to 400 coolies normally employed on Perim could be easily reinforced by 1,000 coolies sent from Aden, Jopp estimated that one way or another all stocks could be removed or neutralised in a couple of days. As an alternative to firing any stacks that could not be removed in time, he thought an even better idea might be to scatter the stacks using explosives.

Aden’s Defence Scheme was updated in 1901. The revised plan for Perim was simple: the detachment would be evacuated. The reason given was that Aden would need all the men it could muster. Therefore following a declaration of war or the outbreak of hostilities the detachment on Perim would be brought into fortress Aden.

This would mean that no attempt could be made to defend the coal stocks in the manner that had been suggested in the Colonial Office circular of November 1886 entitled ‘Local Preparations to be made in anticipation of war’. Furthermore, in accordance with the principles laid down in the circular, the coal stocks would not be in any way interfered with by the General Officer commanding fortress Aden. Or in other words defence or destruction of coal stocks was a naval responsibility.

The threat to Aden (and presumably also to Perim) in 1907 was assessed as being an attack by up to four enemy cruisers. Perim was not mentioned specifically in the contingency plans published that year, but in the revised plans published in February 1909 Perim was still to be evacuated. The action to be taken by the Assistant Resident Perim at any time during transition to war, on receipt of the appropriate order from the GOC Aden Brigade (i.e. the Resident) was to be as follows: He was to assemble all the personnel of the Perim Coal Company, the detachment, those employed by government and any other individuals who wished to leave Perim He was then to load all lighters with such valuable articles as he deemed it advisable to remove and take all the above to Aden, using all steamers, tugs and launches that might be in harbour at the time.

At the Mariannas conference it would be decided to send only one light cruiser, the Emden, into the Indian Ocean. A deployment of this nature had been foreseen by Aden. In 1911 a major revision was made to the Aden Defence Scheme, and particularly with regard to the defence of Perim. The likely threat was reduced to that of a passing cruiser wishing to destroy the cable buildings and instruments and the shore ends of the cable and to make free use of the coaling facilities. Since the destruction of the cable station could only be accomplished by a landing in boats from the cruiser it was felt that the garrison could formidably oppose this by manning carefully selected and concealed positions.

Therefore, with the threat reduced from four cruisers to one, it was laid down in the revised Scheme that the garrison on Perim would now only be withdrawn on mobilisation if the GOC, after consultation with the SNO, considered it absolutely necessary. This again would turn out to be an accurate assessment, seeing that the Emden would be cornered off the Cocos Keeling Islands on 9 November 1914 whilst destroying the cable and wireless stations there.