nuclear device was successfully detonated off the west coast of Australia in the Monte Bello Islands. British hydrogen bomb Hurricane was but the first series of British nuclear weapons tests in Australia. Further tests required a site on land, so Penney visited Australia and chose a site at Emu Field in South Australia for the Operation Totem test series in 1953. Emu Field proved too remote, so Penney selected a more accessible site at Maralinga. The decision to develop a British hydrogen bomb meant that certain scientific information was urgently required and Maralinga was not yet ready, so a second series of tests, Operation Mosaic, was conducted in the Monte Bello Islands in 1956. The subsequent Operation Buffalo tests were carried out at Maralinga in September and October 1956. Penney personally supervised the Totem and Buffalo tests. Penney was aware of the public relations issues associated with the tests, and made clear-speaking presentations to the Australian press. Before one series of tests, Lord Carrington, the High Commissioner of the United Kingdom to Australia, described Penney's press presence: "Sir William Penney has established in Australia a reputation which is quite unique: his appearance, his obvious sincerity and honesty, and the general impression he gives that he would rather be digging his garden – and would be, but for the essential nature of his work – have made him a public figure of some magnitude in Australian eyes". Britain felt the need to quickly develop megaton-class weapons because it seemed that atmospheric testing could soon be outlawed by treaty. As a result, the UK wanted to demonstrate its ability to manufacture megaton-class weapons by proof-testing them before any legal prohibitions were in place. The Prime Minister, Harold Macmillan, hoped to convince the US to change the McMahon Act, which prohibited sharing information even with the British, by demonstrating that the UK had the technology to make a thermonuclear weapon (an H-bomb), and he put Penney in charge of developing this bomb. The Orange Herald bomb was developed and was passed off as a thermonuclear bomb, when in fact it was a boosted fission weapon in which little of the energy came from fusion. The reports were unlikely to have fooled the American observers. The subsequent successful development of British thermonuclear weapons, which coincided with the Sputnik crisis led to the amendment of the McMahon Act, and the re-establishment of the nuclear Special