Britain tested its first atomic weapon on 3 October 1952, detonating a device during Operation Hurricane at the Montebello Islands off Western Australia. The explosion had an estimated yield of about 25 kilotons. It made Britain the third country, after the United States and the Soviet Union, to develop and test a nuclear weapon.

Britain had begun investigating atomic weapons during the Second World War through a project known as Tube Alloys. The work was later combined with the American Manhattan Project, and British scientists contributed to the development of the weapons used against Japan in 1945.

The British government expected nuclear cooperation with the United States to continue after the war. Instead, the US Atomic Energy Act of 1946 severely restricted the sharing of nuclear information. In January 1947, the British government decided to develop an atomic bomb independently.

The programme was directed by physicist William Penney, who had worked on the Manhattan Project. Britain needed a remote test site, and the Australian government agreed to the use of the Montebello Islands.

For Operation Hurricane, the device was placed inside the hull of the Royal Navy frigate HMS Plym. The arrangement was intended partly to examine the effects of a nuclear weapon brought into a harbour aboard a ship, a possible form of attack that concerned British planners.

At 7.59 a.m. local time on 3 October, the device exploded* Plym*’s waterline below. The frigate was destroyed, and the explosion left a crater on the seabed.

The successful test confirmed that Britain’s independent programme had produced a working atomic weapon. It provided the technical basis for the nuclear weapons that subsequently entered service with the Royal Air Force and established Britain as a nuclear-armed state.