The load – which was part of a building under construction on 3 November 2007 at Hertfordshire Regional College in Turnford, near Cheshunt – came down heavily beside part of the campus regularly used by students.

The impact also demolished the site boundary fence and damaged a college building.

London Tower Crane Hire & Sales Limited, the company which owned and operated the crane, appeared at Hertford Magistrates’ Court yesterday and admitted breaching health and safety laws.

The company, which has a head office at Elstree Way, Borehamwood, Hertfordshire, was fined £18,000 and ordered to pay £15,837.45 in costs.

HSE Inspector Norman Macritchie said: “It was a matter of good fortune that no-one was injured in this entirely avoidable incident.

“Those undertaking lifting operations have absolute duties to plan, supervise and carry them out safely.

“Maintenance staff had indentified safety-critical faults in the crane yet simple controls needed to prevent use of defective equipment were not implemented.

“Poor communication and teamwork, together with inadequate supervision, all contributed to this incident.

“This case has important lessons for all those operating lifting equipment and especially tower cranes.”

A London Tower Crane Hire & Sales Limited statement said:  “In response to this incident we have implemented dynamic and robust safety systems addressing the specific failings of this incident and wider risks across our operations.

“We welcome the comments from the HSE and have continually strived since this incident in cooperation with the executive to learn these critical lessons.

“We are satisfied that the circumstances which contributed to this incident in November 2007, no longer exist within our business and that our systems and procedures are currently industry leading.”