Operator Rick Jaeger-Fozard was killed in the collapse at the Kimberly Access yard next to the motorway near Heathrow.

Now trade body the International Powered Access Federation has written to Employment minister Esther McVey calling for interim results from the investigation to be revealed.

The machine involved was a Genie Z-135/70 which was removed by HSE experts for tests.

IPAF said there are around 200 similar machines used regularly on sites in the UK.

The HSE said that if any findings of their ongoing investigation revealed that workers were at risk then they would issue an alert.

The letter from IPAF CEO and managing director Tim Whiteman states: “It is now five months since the fatal accident took place and no information or data has been released to the industry.

“This delay is not considered acceptable by an industry that prides itself on the highest safety standards and professionalism in order to ensure that people working at height remain safe.

“This leads to confusion and concern in the industry and can even lead to people considering the use of alternative, less safe methods of performing temporary work at height.”

IPAF is now demanding an urgent review of the investigation and new measures to be introduced which speed-up the release of accident findings.

A spokesman for the Health and Safety Executive said: “Our investigation into this incident is ongoing. Like all HSE investigations, it is a criminal one, and therefore it would not be appropriate to comment further at this stage.

“It is important to stress though that should our investigations reveal information that we felt it necessary to publish, for example if we felt workers were at risk, we would take action, including alerting dutyholders, at the earliest opportunity.”