 Hallowes was born in Kensington, London, the son of Edward Price Hallowes, a partner in Twiss, Browning & Hallowes of London, importers of Dry Monopole champagne, and Aileen Macleod of Adelaide, South Australia.He was educated at the Aldro prep school, Eastbourne, the Lyceum Alpinum Zuoz in Switzerland, and at Jesus College, Cambridge, but left without a degree.During the Second World War, Hallowes initially served with the 2nd Battalion, the Gordon Highlanders in the defence of Malaya against Japan in 1942.