sub

Individually, the UK’s 86 local government pension schemes vary in size, from Greater Manchester’s massive £30bn fund all the way down to several schemes which are “sub-£1bn”, according to Joanne Donnelly, board secretary at the Local Government Pension Scheme Advisory Board.

The log of these exchanges could reveal if there were any indications that the sub was failing.

The vessel also had an acoustic monitoring device - essentially mics fixed to the sub listening for signs it was buckling or breaking.

But he said he was highly sceptical that this would have provided enough time for the sub to return to the surface.

A more pertinent subsea sound was detected by the US Navy’s sonar system at the time the sub went missing - an acoustic signal consistent with an implosion.