The National Energy System Operator (Neso) has denied allegations that staff engaged in a cover-up over decision-making during June's heatwave, after a Tory MP accused senior managers of risking blackouts to protect the organisation's reputation.
Whistleblower allegations
Shadow energy secretary Claire Coutinho told parliament that whistleblowers claimed control room staff were ordered to forgo normal note-keeping to avoid creating a full audit trail of efforts to stabilise the power system. Whistleblowers also alleged that corporate affairs team members pressured operators to make decisions that would protect Neso's reputation.
"If true, this is nothing short of a scandal," Coutinho said. Neso has brought in independent investigators from law firm Eversheds Sutherland to examine the accusations.
Heatwave challenges
During the last week of June, a high-pressure "heat dome" caused wind turbines to slow, gas plants to falter, and French nuclear exports to drop, while demand for air conditioning surged. Neso issued emergency measures for the first time in a summer period, spending nearly £800,000 on demand reduction between mid-April and mid-July, according to the Financial Times.
Grid frequency fell to the edge of operational limits (49.8Hz to 50.2Hz) for almost an hour on 23 June, reaching a low of 49.66Hz—still above the statutory limit of 49.5Hz. A former employee told the Guardian that such prolonged low frequency suggested the operator was running low on palatable options before more serious interventions like disconnecting factories.
Neso's response
Craig Dyke, a Neso director, said that although the heatwave led to "sustained pressure on power systems" and "tight operating margins," no customer demand was disconnected, frequency remained within statutory limits, and no lines or cables were overloaded.
Neso controllers breached normal limits on trading power across subsea cables several times, including an emergency call for 500MW from the Netherlands on 24 June. Payments for emergency electricity from gas plants reached millions of pounds, adding to carbon emissions.
Reputational pressure
The former employee said the pressure to avoid reputational damage is significant. Neso became state-owned after the government bought it from National Grid for £630m in late 2024. Under previous ownership, engineers knew a misstep could hit National Grid's share price; now they face expectations to balance supply and demand without hiccup as more renewables come online and Labour pushes for a 2030 green energy target.
"Whether there were direct orders to cover up a scandal or not, individuals are potentially being put in an invidious position that might inhibit them from taking the correct action," the former employee said.
Neso CEO Fintan Slye said policies and procedures are in place to prevent such influence, and the Eversheds investigation will be shared with Ofgem and the government and ultimately published.
