Independent investigation concludes allegations against NESO were unsubstantiated

19 October
Press release About NESO 19 Oct 2026
Control Room cropped

Key facts
Independent investigation concludes no evidence to substantiate allegations against NESO.
No evidence of record manipulation or concealment.
No evidence that Corporate Affairs influenced operational decisions.
Preliminary report of the separate Ofgem-commissioned technical review into electricity system operation during the June 2026 heatwave also published today.
The preliminary report sets out chronology to date and confirms frequency did not deviate outside statutory limits at any point. The final report is due in December.

Today the National Energy System Operator (NESO) responds to the conclusion of an independent investigation conducted by Eversheds Sutherland (International) LLP into allegations raised around operational decision making and record keeping in NESO’s Control Room.

The investigation concluded that there was no evidence of inappropriate influence over operational decisions or that control room records were altered or inappropriately managed in any way, including to avoid public scrutiny.

The report did identify areas requiring improvement, including in how colleagues can raise concerns and how those concerns are acted upon. NESO accepts the recommendations in full and is developing an implementation plan which builds on actions already underway.  Delivery of the plan will be overseen by the NESO Board.  

The investigation was undertaken independently by Eversheds Sutherland (International) LLP. Its work was overseen by an independent panel chaired by Jayne Scott, Chair of NESO’s Audit and Risk Committee, alongside Akshay Kaul, Ofgem Director General for Infrastructure, and Siobhan Duffy of UK Government Investments.

Paul Golby, Chair of NESO, said: 

“These were serious allegations and the Board were explicit that they needed to be investigated independently and comprehensively. We are grateful to everyone who contributed to that work.

“The investigation’s findings are clear that there was no evidence to substantiate any of the allegations around inappropriate influence over decision making or inappropriate record keeping processes.

“The Board will oversee the development of plans to address the issues raised in the report and ensure these are implemented as a matter of urgency.” 

Fintan Slye, NESO Chief Executive, said: 

“We welcome the findings of ESI’s independent and rigorous investigation.  It is constructive in identifying areas where we could improve how colleagues can raise concerns and how we respond to them. I want all colleagues at NESO to feel heard. We will act on the recommendations, working closely with our Trade Unions, and be open with colleagues about the progress we make.” 

Today, the preliminary report of the separate Ofgem-commissioned technical review into electricity system operation during the June 2026 heatwave was also published.

The preliminary report sets out the evidence reviewed and the chronology established to date.  It confirms frequency did not deviate outside statutory limits at any point. The review remains ongoing and final conclusions, recommendations and lessons learned will be set out in the final report.

Kayte O’Neill, NESO Chief Operating Officer, said 

“NESO is committed to continuous improvement, and we welcome the preliminary report into the operation of the electricity system during the extreme heat at the end of June. This was a very challenging period for the power system in Great Britain, and for power systems around Europe. Our Control Room engineers did an outstanding job, ensuring that no customers were disconnected and the frequency always remained within statutory limits.

“The next phase of the review will undoubtedly provide further learnings for the operation of system and market. It will be important that these are adopted to strengthen the resilience of our energy system for future extreme events.” 

ENDS

About NESO

NESO is Britain’s National Energy System Operator. We operate today’s electricity system and design tomorrow’s energy system.

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Notes to editors:

 Independent investigation by Eversheds Sutherland (International) LLP

  • NESO commissioned an independent investigation in July 2026 following allegations raised about operational decision-making and record-keeping during the period of system stress between 22 and 26 June 2026. 
  • The investigation was conducted by Eversheds Sutherland (International) LLP and examined allegations relating to: 
    • The retention and management of operational records 
    • Documentation of operational decision-making 
    • The use of working documents during periods of system stress 
    • Alleged influence on operational decision-making by Corporate Affairs personnel. 
  • The investigation was overseen by an independent panel comprising representatives from NESO's Audit and Risk Committee, Ofgem and UK Government Investments. 

Technical review commissioned by Ofgem

  • A separate review was commissioned by Ofgem into the operation of the electricity system during the heatwave at the end of June. 
  • The review is examining how Great Britain's electricity system operated during that period, including system conditions, operational decisions and market activity. 
  • The preliminary report is a factual account of events, evidence and chronology established at this stage. 
  • The report analyses the system frequency throughout the period and concludes that at no time was the frequency outside the statutory limits of 50.5-49.5Hz. 
  • The review remains ongoing. Final conclusions, recommendations and lessons learned will be contained in the final report.