Whether or not a caisson was used, the oil from the containment assembly would then pass through a manifold a sort of switching yard for pipes to one or more floating risers leading to the surface and held vertical by buoys.

ECONOMIST: Fixing oil wells

Mr Hurley, a former Scotland Yard borough commander, then requested an independent report and sought advice on whether to abandon Siren and examine switching to the systems used by other forces in the region.

BBC: Surrey Police scrap multimillion-pound computer system