A 100ft crane collapsed killing two men after an inexperienced workman loosened the bolts holding it together, an inquest heard.

Stephen Boatman, 45, from Reading, and Gary Miles, 37, from Crowthorne, near Bracknell, plummeted to their deaths after the crane being used in the £11 million construction of Highdown School, Durrington, fell apart on February, 11, 2005.

Both men were on top of the crane when it collapsed and died instantly from head and chest injuries.

An inquest jury last night delivered verdicts of accidental death for the men after hearing how David Smith, 55, of Weybridge, loosened 16 heavy duty bolts that were holding the cranes together.

Mr Smith was left dangling halfway up the machine unconscious but later recovered in Worthing Hospital.

Major Crime Branch police officers had earlier ruled out manslaughter charges against both Mr Smith and W D Bennett, the Gloucestershire company that had been carrying out the work.

The inquest heard evidence from 11 witnesses, including those who saw the drama unfold just after 10.15am.

Three workmen on the ground described hearing loud cracking noises as the crane slowly tipped forward, followed by popping sounds as the bolts gave way one by one and then a crash as the top part of the crane fell, hitting another crane on its way.

Mr Smith, Mr Boatman and Mr Miles had begun "derigging" one of two cranes being used in the construction.

Mr Boatman had told Mr Smith to loosen the bolts, known as "detorquing", in preparation for its total dismantling the next day.

However, the inquest heard how Mr Smith may have misinterpreted Mr Boatman's instructions to loosen the bolts until they were "hand tight" with an industrial tool.

A tearful Mr Smith admitted he possessed no formal qualifications for crane dismantling but the jury heard he was an experienced crane driver.

Neither Mr Boatman or Mr Miles possessed any formal qualifications for dismantling cranes and the inquest heard that none existed.

However, both men had between ten and 13 years experience of doing the job and were described as "experts" during the inquest.

When asked if he had undone the bolts too far, Mr Smith told the inquest: "I did take them off from where the nut sits on the steel work, further down the bolt."

He went on to say he may have been confused about what Mr Boatman had meant by "hand tight".

Mr Smith undid the bolts from one side of the crane and when the machine was rotated in preparation for him continuing on the other side it collapsed, sending Mr Boatman and Mr Miles to their deaths.

Accident investigators later confirmed that a bolt near the top of the crane had failed first, followed by a "domino effect" of other bolts further down because of the force of the machine turning.

Managing director Bennett Edward Seager told yesterday's inquest his company no longer carried out detorquing on its cranes.