Operator Rick Jaeger-Fozard was killed when a Genie Z-135/70 collapsed at the Kimberly Access yard next to the M25 motorway near Heathrow last summer.

The hirer decided to keep its Genie fleet grounded even after the HSE issued a safety alert in February warning owners and operators that the machine must be calibrated correctly.

Kimberly has now devised a secondary safety system to ensure the machines are calibrated correctly.

It will now re-introduce the fleet in June following a coroner’s inquest into the tragedy due later this month.

Kimberly Group CEO Geraldine Unsworth has written to customers stating: “During the past months we have been placing great emphasis on investigating the cause of the accident and reviewing all aspects of the Z135 operating systems under the guidance of independent forensic engineers who specialise in this work.

“As a result of a great deal of work and input we are well versed in the cause of the accident, the details of which we cannot comment on as this will be the subject of scrutiny by a coroners’ inquest to be held in May.

“We can however inform you that Kimberly and its engineering advisors have devised a secondary safety system which has been reviewed by independent bodies who conclude that had this system been fitted to the fateful Z135 then the accident would not have happened.

“Furthermore, in order to continually improve the Z135 operating standards and to encourage our clients to adapt safer working practices, in readiness for the machines returning back to work we will be introducing new procedures and standards for the hire process and on-site handover of machines.

“Subject to completing certain self imposed hurdles and testing we are aiming to deploy the Z135 fleet on 1 June 2014 which out of total respect to Rick’s memory and his family is after the coroner’s inquest.”