A major report has found that staff at the National Energy System Operator (Neso), the Labour-founded quango managing the grid, feared their concerns were being ignored by bosses more interested in 'keeping the Government happy".  

The investigation was launched after whistleblowers claimed Neso had tried to cover up how close Britain came to blackouts during the summer heatwaves.

Energy minister Michael Shanks insisted at the time that electricity supplies remained sufficient and that no customers lost power.

Neso – a government body set up by then energy secretary Ed Miliband – later ordered an independent review into the claims.

But witnesses claimed their concerns over energy blackouts went 'largely unheard' because of 'the need to keep external stakeholders (customers, Government and the regulators) happy' according to the report, which was published on Monday.

Independent investigators found this contributed to 'a culture of perceived non-response' where employees 'avoid raising concerns altogether, perceiving little point in doing so when nothing appears to change'.

Referencing the whistleblowers, they added: 'This perception is itself a cultural and governance concern and helps explain why individuals felt the need to raise concerns externally.'

The report notes that in one instance, a witness told an official sitting in the control-room, 'don't feel under pressure from them' regarding external stakeholders questioning when alerts warning of shortages in the system would be made.

They later advised the official, 'don't let DESNZ pressure you, mate', in relation to Government's Department for Energy Security and Net Zero.

The report concluded that these allegations 'are not supported by the weight of evidence' but that Neso ignoring complaints led to whistleblowers raising 'concerns externally'.

A separate preliminary review from Ofgem, Britain's energy regulator, found electricity did not drop under acceptable levels.

But shadow energy secretary Andrew Bowie said on Monday that the report 'raises more questions than it answers' about Neso.

He said: 'Far from clearing the heads of Neso or this Labour government, this report raises more questions than it answers about the culture, management and operational independence of the organisation tasked with keeping the lights on in this country.

'It also confirms what we Conservatives have been saying all along - that the net zero transition and the increased reliance on renewables is making the job of ensuring the grid continues to operate much more difficult due to the lack of flexibility and inertia in the system.'

Mr Shanks said: 'The independent investigation shows none of the allegations can be substantiated by the evidence and Ofgem's report shows the system continued to operate and customer demand was met throughout the summer.

'However, the independent review raises areas for cultural improvement in NESO where we expect significant action without delay. We will keep progress under close review.'

It comes as research published on Monday reveals Britain is one of the least energy secure countries in the world, ranking 41st out of 187 countries tested.

According to research from think tank the Adam Smith Institute, Britain sits behind the US, Canada, France and Japan in the G7 for energy security, and behind lower-income countries Romania, Azerbaijan, Serbia and Ukraine globally.