ONE SENIOR industry source said the likely cause of the collapse was a catastrophic failure of the machine's slew ring - the turning gear which enables the top of the crane to rotate.
He said: 'According to the people I've spoken to, this looks like where the problem was. If the bearing and bolts failed the crane would just topple over.'
A crane expert said: 'It has clearly snapped at the slew ring. Investigators will be looking at the bolts that attach the slew ring to the upper part of the mast.'
One eyewitness said: 'I heard a big bang. I turned around and the crane driver stood up and then he was thrown out of the cab, somersaulting into the air.'
Another expert added: 'If the driver was strapped in the effects should have been no more that a 15 mph car accident. The seat has come out of its fastenings but it is still in the cab.
'If he'd have been st rapped in he should have got away with cuts and bruises - a few broken bones at most.'