In Biggles in Australia, Colonel MacEwan was an Australian security officer. Air Commodore Raymond gave his contact to Biggles as he was about to depart for Australia. Part way through the investigations, after the arrests of Roth at Tarracooma, Biggles felt that it was time to report his findings to the Australian security authorities. Accordingly, he took the Halifax alone from Darwin to Sydney to see MacEwan. Later, MacEwan issued orders to Darwin to ground the Auster J1 Autocrat belonging to the spy network.
MacEwan came up to Darwin with Biggles. There, Algy told them that Ginger, Bertie and Cozens had gone on to Daly Flats. Concerned that they may get into trouble, Biggles, MacEwan and two policemen followed after them in the Otter. They arrived towards the tail end of the "Battle of Daly Flats". The settlement had come under attack by a party of Australian aborigines. Smith, Ivan and some others of the spy network had already been killed while Ginger, Bertie and Cozens were trapped in a house, holding off the attackers with tear gas.
MacEwan took charge of the mopping up operations. A search of Daly Flats revealed documents and other evidence detailing the spy network in Australia which was used by the authorities to put an end to its activities.