Fear have been raised over the safety of wind turbines after reports showed two fell because of faults.
The giant masts crashed down on farmland amid initial rumours of sabotage and claims they had fallen victim to severe weather.
Documents have now revealed that the towers actually toppled over due to defects and mistakes in the construction process.
A 115ft (34 metre) mast at East Ash Farm, Bradworthy, in Devon, tumbled in January 2013, prompting claims of foul play from the local parish council.
Around the same time, a 60ft (18-metre) tower sited at Winsdon Farm, North Petherwin – the family farm of Liberal Democrat Cornwall Councillor Adam Paynter – also came loose from its moorings and fell.
Subsequent investigations by both manufacturers identified further defects and prompted warnings to other sites, including in Somerset, Devon and Cornwall.
Glasgow-based Gaia Wind wrote to owners and overhauled its entire first generation fleet.
Canadian firm Endurance Wind Power said it was also concerned about machines on dozens of locations.
Initial reports suggested high winds may have been responsible for the failures but restricted reports by the Healthy and Safety Executive (HSE), obtained under the Freedom of Information Act (FoI), have blamed the way the towers were secured.
Specialist inspector Darren Nash concluded that the first generation model of the turbine sited in Cornwall appeared “susceptible to fatigue failure” and said Gaia Wind had found “ten units with existing defects” out of the company’s 70 or 80 turbines.
“A plan of remedial actions is in place to address these units,” he wrote.
Endurance Wind Power, makers of the E3120 turbine which fell in Devon, identified a further 29 turbines that might have been affected by a problem with the foundations.
Mr Nash said it had fallen because Dulas – the installation company – had used “cosmetic grout” to cement the structure in place and not the “prescribed” substance.
On his visit to the site on May 8, more than three months later, he also noted that the turbine had already been “re-instated using the original anchor bolts and studs.
He added that “no evidence remained to assist investigation”, recommending that Edurance improve its quality assurance procedures.
Dr Philip Bratby, a retired nuclear scientist and spokesman for the Campaign to Protect Rural England, said several wind turbines in Devon were sited much too close to roads and factories and “pose a real threat to the public”.
“It is not the responsibility of the Health and Safety Executive at the planning stage – they can only get involved after an incident occurs,” he added.
“It has been apparent to me for a long time that most developers of wind turbines and wind farms do not do a proper assessment of safety and of the risks to the public from wind turbines and none of them have acceptable quality assurance procedures in place.”
Alan Dransfield, a campaigner based in Exeter, who visited the Devon site days after the incident and later secured the two reports, said he was “disappointed”.
He criticised the response from the HSE, which rather than publish their findings, said the documents were not available in electronic form then only released the papers after a formal FoI request.
“These wind turbines which collapsed were unsafe and unfit for purpose,” he added.
“We should not have to resort to Freedom of Information Act to find this out.
“The root causes were not high winds but poor design, inferior materials and a systemic failure through the chain of command.”
Martin Paterson, spokesman for Gaia-Wind, said:
the firm and its reselling agents inspected all “first generation” towers, which were designed to the “prevailing engineering standard of the time”.
“This standard was superseded in early 2011 and this tube tower design is no longer available for sale or installation,” he added.
“Our second generation towers are designed to current industry standards reflecting the development of more demanding design protocols in this field.”
Dulas declined to comment on the findings
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