The Green Granite prototype, known as Short Granite, was tested in the first of the Operation Grapple test series, Grapple 1. The bomb was dropped from a height of by a Vickers Valiant piloted by Wing Commander Kenneth Hubbard, off the shore of Malden Island in the Pacific on 15 May 1957. It was Britain's second airdrop of a nuclear bomb after the Operation Buffalo test at Maralinga on 11 October 1956, and the first of a thermonuclear weapon. The United States had not attempted an airdrop of a hydrogen bomb until the Operation Redwing Cherokee test on 21 May 1956. Short Granite's yield was estimated at , far below its designed capability. Despite its failure, the test was hailed as a successful thermonuclear explosion, and the government did not confirm or deny reports that the UK had become a third thermonuclear power. When documents on the series began to be declassified in the 1990s, they were denounced as a hoax. The reports were unlikely to have fooled the American observers.