The workers suffered various injuries including spinal fractures, broken shoulders, fractured ribs and cuts and bruises. Nearly five years after the incident occurred, one of the workers has been unable to return to work, and another still suffers from back pain.

The Central Criminal Court ordered the company to pay £27,500 on Monday.

The collapse occurred in May 2003, when Excelcare Developments Ltd was building a four-floor residential home for the elderly at Park Avenue, Bromley. Between 13 and 15 May, a crane was used for unloading concrete blocks and beams at the back of the development. On 15 May, blocks were lifted onto the second floor, which was under construction.

Moments after a second load was lowered on to that floor, it collapsed, which in turn led to the collapse of the first and ground floors below. Four workers who were on the second floor fell to the basement area along with debris, material and blocks.

Amanda Huff, HSE Inspector said: "It is unacceptable that workers have to be seriously injured before companies realise that they have to comply with health and safety legislation. This incident could easily have been avoided by proper planning and by using a suitably experienced and trained workforce."