Sea Gem made the first British discovery of natural gas in September 1965,[1] although the find was too small to be commercially profitable.
Sea Gem was originally a 5,600 ton steel barge, converted to function as an oil rig by BP in 1964.
The conversion involved fitting 10 steel legs, making it possible to provide a stable platform by raising the barge 15 metres (49 ft) above the water's surface.
[1] As a result of a public inquiry into the accident,[2] several changes were made in order to improve the safety of oil rigs.
The inquiry concluded brittle fracture in part of the suspension system linking the hull to the legs was the cause of the collapse.