James Richards suffered broken bones in his back, a broken arm, pelvis and rib, a punctured lung and had to have his spleen removed.
He was hospitalised for 22 days and bed-bound for a further three months. He has not returned to work since and still suffers pain due to his injuries.
A Wimbledon-based building restoration contractor and a fire escape business in Croydon were fined at the Old Bailey yesterday following the incident.
The court heard that Triton Building Restoration was the principal contractor and had subcontracted the restoration of the cast iron fire escape and external repair and painting of Abingdon Villas in Kensington to Fire Escape Ltd.
On 4 December 2008 Richards fell six storeys down an unguarded light well in the centre of the building.
Triton Building Restoration of 14 Saxon Business Centre, Windsor Avenue, Merton was fined £5,000 with £11,339.55 costs and Fire Escape Ltd of 141 Queens Road, Croydon was fined £3,500 with £11,300.55 costs.
HSE inspector Monica Babb said: “This was a serious and entirely preventable incident that will affect Mr Richards for the rest of his life.
“Companies should ensure that safety precautions to prevent falls from height are monitored to ensure that they are not removed where access to work at height is still possible.
“Falls from height are still the biggest killer in the construction industry and the biggest single cause of death and serious injury at work. In 2008/9, there were 35 deaths and more than 4,000 major injuries caused by falls from height.”