James Whelan, 31, from Wimbledon, fractured parts of his spine and pelvis, broke four ribs and bruised his lung in the incident in Wandsworth on 8 August 2013.

Westminster Magistrates’ Court heard that Bowmer & Kirkland was responsible for refurbishing and extending an existing Sainsbury’s store.

Whelan, who was working for a scaffolding subcontractor, was walking in an area linking the roof space of the old store with the new extension when he stepped from an exposed timber walkway onto a section of dusty plasterboard that he assumed was the same material as the walkway.

He crashed through the fragile material and a suspended ceiling, ending up on a stairway beneath the roof space.

Magistrates were told that Bowmer & Kirkland sought to control the risks posed by the fragile area by restricting access to the walkway.

Instead more should have been done to physically mitigate the chances of a fall occurring in the first place, such as providing a better, properly guarded walkway or hard covers for the fragile materials.

Bowmer & Kirkland Ltd, of Belper, was fined £6,000 and ordered to pay a further £1,428 in costs after pleading guilty to a single safety breach.

After the hearing HSE Inspector Gavin Pugh said: “The hazards presented by fragile surfaces and open edges are clear, and it is common knowledge that falls from height account for almost half of all deaths and serious injuries on construction sites.

“As such, companies like Bowmer & Kirkland should be fully aware of what needs to be done to adequately protect workers.

“The safety standards surrounding the walkway and fragile area fell some way short on this occasion, and it could have cost the scaffolder his life.

“He suffered painful injuries that still cause him pain and discomfort, but he could just as easily have been killed.”