Westminster Magistrates’ Court heard how Jair Morales was installing plywood boards covering holes on the third floor of a building at a construction site in Uxbridge, Middlesex, when he fell 3.95m to the floor below. He suffered fractures to his pelvis and arm and has been unable to work since the accident.

No steps had been taken to prevent him falling through the opening as he installed the plywood boards.

An investigation by the Health & Safety Executive (HSE) found that Kier Construction Ltd had failed to ensure the work was properly planned and carried out in a safe manner.

Kier Construction, of Tempsford Hall, Bedfordshire, pleaded guilty to breaching section 4 (1) of the Work at Height Regulations 2005. It was fined £400,000 and ordered to pay costs of £1,534.

Speaking after the case, HSE inspector Owen Rowley said: "This incident could have been a lot worse. The system that Kier Construction Ltd has in place to control the risk from installing the protection for openings was not implemented on site, ultimately resulting in the accident.

"The risks of working at height are widely recognised throughout the construction industry. This case highlights the importance of ensuring that all work at height is properly planned and carried out safely."

You can doenload an HSE Brief Guide to Working at Height here.