The "Bomb"

Dropped by a Valiant B1 bomber (XD 818 of Squadron No. 49) The aircraft was piloted by Wing Commander K. G. Hubbard. The device detonated after 52 sec of free fall.

This was Britain's first test of a radiation implosion thermonuclear bomb design. The device, named Green Granite Small, weighed 10,000 lb and used a modified Red Beard primary (called "Tom") and a lead-encased lithium deuteride secondary (called "Dick"). Most of the yield was from the secondary, providing evidence of successful radiation implosion, but the yield was far below the predicted value (about 1 megaton was expected).