Operation Grapple was conducted in several parts to test weapons produced in Britains thermonuclear development programme. It followed from the Operation Mosaic series of fusion bomb tests, held in mid 1956 off Monte Bello Island (Australia) and the Operation Buffalo test series held on mainland Australia in late 1956. The first Grapple series tests were on 15 May, 31 May and 19 Jun 1957 involving air drops from Valiants of 49 Squadron on Malden Island. The second Grapple tests were held around Christmas Island between Nov 1957 and Sep 1958 also using an air drop from Valiants of 49 Squadron and balloon supported detonations. Canberras, and the Whirlwinds of 217 Squadron were also present.

In addition to the RAF presence, after re-fit with an angled flight deck, the ex Light Fleet Carrier, HMS Warrior sailed from HMNB Portstmouth during February 1957 to provide a maritime arifield. The Ships Flight Whirlwind HAR.3 took part in the operation.