Lyon led a Services Reconnaissance Department party of twenty-two men. They left their base in Australia aboard the British submarine on 11 September 1944. When they reached the island of Merapas, which was to be their forward base, it was discovered to be inhabited. To ensure that their stores would remain undiscovered by the natives one of the officers from the "Porpoise", Lieutenant Walter Carey, remained on Merapas as a guard. The party then commandeered a Malay junk named "Mustika", taking the Malay crew aboard the submarine. The SRD men transferred their equipment to the junk and the "Porpoise" departed. Lyon decided to drop off four more men with Carey: Corporal Colin Craft, Warrant Officer Alf Warren and Sergeant Colin Cameron.