Noel Doyle, 32, from Hammersmith, suffered a shattered right elbow, broken vertebrae, fractured pelvis and ribs, and damage to internal organs in the incident at St George Wharf in Vauxhall on 10 February 2009.
He fell almost 10m onto a concrete staircase from a platform when it gave way when a lifting procedure was screwed up.
J Reddington Ltd (JRL), of Borehamwood, which was responsible for the structure, has been fined after a prosecution brought by the Health & Safety Executive (HSE).
On the day of the fall Mr Doyle was helping two other JRL employees, one of whom was a foreman, to raise a temporary work platform inside a concrete shaft to house a stairwell within a building under construction, which was known as 'Block A'.
The platform was lifted from one floor to another by a crane using four lifting chains before being locked in place in the shaft to enable the next level to be constructed. It had been raised from the fourth to the fifth floor level when the crane operator was inadvertently instructed by the foreman to take the chains away while one of them was still attached. Because the platform was lifted by only one corner it fell apart.
Of the three workers standing on the platform at the time, two managed to jump to safety but Mr Doyle was unable to do so. He fell into the shaft beneath with parts of the platform and equipment that had been stored on top raining down on him.
Mr Doyle required extensive treatment and physiotherapy, and has been left with limited movement in his right arm because of the elbow injury. He is no longer able to work in construction.
The HSE investigation identified that the incident was caused by the failure of the foreman, who was also acting as a banksman, to ensure that all the lifting chains had been properly disconnected from the platform before instructing the crane driver to take them away.
JRL failed to plan, manage and monitor construction work carried out under its control in a way that ensured that, so far as was reasonably practicable, it was carried out without risks to health and safety. The company also failed to manage the design, construction, maintenance and use of the temporary core platforms throughout Block A.
J Reddington Ltd, of Elstree Way, Borehamwood, Herts, was fined £70,000 and ordered to pay £22,193 in costs after pleading guilty to breaching Section 2(1) of the Health and Safety at Work etc. Act 1974.
HSE Inspector Loraine Charles said: "Noel sustained serious injuries as a result of a fall that was entirely preventable had work involving temporary platforms been better planned and managed by JRL. He fell a significant distance and could easily have been killed, as could his two colleagues who were with him on the platform."