FINTAN SLYE MUST EXPLAIN THE REAL COST OF BRITAIN’S GRID DELAYS

HOPE to Save Our Countryside | Evidence checked 7 November 2026

Fintan Slye, NESO’s Chief Executive, should answer a straightforward question: what happens to the cost of Clean Power 2030 when the grid is not ready when the plan needs it?

On 5 November 2024, he submitted NESO’s clean-power advice to the Secretary of State and Chris Stark, presenting it as supported by expert whole-system analysis. [1]

We are examining that advice against project programmes, connection dependencies and operating costs. The public deserves a clear account of what remains deliverable, what has slipped and what those changes mean for bills.

Years behind the dates that mattered

The National Audit Office’s September review found that, as at March 2026, 50 of 56 ongoing essential projects were forecast beyond NESO’s original optimal delivery dates. Some were years later. Four were expected after 2030. Missing an optimal date does not automatically mean missing 2030. [2]

That distinction matters. Infrastructure can arrive before the political deadline while arriving too late to deliver the savings expected from it. The cost of the intervening period needs to be calculated and explained.

Our substation and connection investigation follows the engineering chain: transformers, bays, circuits, protection, testing and usable export capacity. A planning approval or a revised offer is only one step towards electricity reaching a customer.

The earliest date assumes away delivery risks

The June 2026 Beyond 2030 technical report bases recommendations on earliest theoretical dates, defined as “assuming delivery risks do not apply”. National Grid also supplied dates with a 50% likelihood of delivery, accounting for planning, supply-chain and access risks; not every transmission owner supplied them. This is a 2030s investment assessment, not proof of the 2030 target. [3]

An investment may be needed urgently, yet its earliest possible completion may be an unsuitable basis for promising when its benefits will arrive. Mr Slye should show both the earliest and realistic delivery ranges, and the financial consequences of the gap.

The costs are already reaching the system

NESO’s September report records £553 million in total balancing costs and 1.8 TWh of wind constrained off. High wind, low demand, network outages, restricted transfers and replacement-energy prices contributed. The whole sum cannot be attributed to delays or payments to wind farms. [4]

It demonstrates why generation and networks must be delivered together. Cheap electricity at the generator is only useful to a customer if the system can deliver it when needed.

NESO should calculate the additional cost of delayed reinforcement using current programmes and a consistent model. Consumers should be able to see how much of the expected benefit survives a later delivery date.

Acknowledging problems must change the conclusions

NESO has acknowledged that generation developed faster than the network, and that planning and supply-chain delivery are critical. Parts of its analysis have also been updated. [5]

The unanswered question is how far those changes alter the national delivery and consumer-cost conclusions. Our review has not identified a complete published reconciliation incorporating every current holdup. NESO should provide it, with a clear statement of the evidence cut-off.

The NAO also identified gaps in overall accountability and in assessing generation and transmission options together. [2]

Mr Slye leads the organisation providing system advice. Transmission owners build the assets, planning authorities decide consents, Ofgem regulates investment and ministers set policy. That shared responsibility makes a joined-up public account more necessary.

What Fintan Slye should publish

• The changed dates: original and current commissioning programmes, including partial energisation and usable capacity.
• The realistic risks: delivery ranges allowing for planning, equipment, labour and construction outages.
• The revised costs: consequences for constrained generation, replacement fuel, system services and consumers, with overlapping charges removed.
• The decision record: who accepted each material change, what contingency was funded and what evidence would trigger a different course.

Confidence in a target is not enough. The public needs a current, costed programme that can be checked against physical delivery.

Make them show the evidence

Families and businesses need affordable, dependable electricity. They deserve decisions tested against infrastructure that can actually be built, financed and operated.

Our campaign calls for an independent national assessment of the full costs and impacts of the statutory targets. [6]

Ask your MP to demand the updated delivery and cost evidence. Share this article with the people being asked to pay for the transition.

Read our earlier investigation: The £70 billion grid question.

Primary sources

1. Fintan Slye’s covering letter, 5 November 2024
2. National Audit Office, September 2026: paragraph 2.4 and key facts
3. NESO June 2026 technical report, printed pages 10–11
4. NESO September 2026 Monthly Balancing Cost Report
5. NESO’s September acknowledgement of delivery dependencies
6. Shane Oxer’s parliamentary petition