High prices
Wed 9 Sep · Thu 10 Sep · Fri 11 Sep
Research notes
Figures are for London unless they say otherwise.
What happened. Wed: average 32.2p, max 54.5p at 18:30. Thu: average 32.0p, max 47.5p. Fri: average 34.4p, max 61.0p at 18:00, 71.4p in Northern Scotland. Minimums of 21p to 27p: no cheap hours.
Likely causes
- Gas jumped on a Gulf escalation. Catalyst, 9 Sep: "Iranian ballistic missile strikes on a US base in Jordan, attacks on ten ships, the US destruction of five Iranian oil tankers" sent Brent through $100. NBP day-ahead went 182p (7 Sep) to 189.25p (8 Sep) to 197.65p (9 Sep) to 205.25p (10 Sep). Day-ahead baseload power went from £72.76 (Fri 4 Sep) to £154.45 (8 Sep, for 9 Sep), "a rise of 112% across two sessions", then £163.50 (for 10 Sep) and £176.00 (for 11 Sep), the period's high (confirmed by source) Catalyst 9 Sep, Catalyst 10 Sep, Catalyst 11 Sep
- The US strikes on Iranian tankers on 8 Sep and the Iranian strike on Muwaffaq Salti air base in Jordan on 9 Sep are independently recorded (confirmed by source) Wikipedia: September 2026 US strikes on Iran. On 10 Sep Houthi forces seized the Red Sea port of Mocha (Catalyst 11 Sep). On 11 Sep drone strikes shut Saudi Arabia's east-west pipeline Morning Advertiser, 18 Sep 2026
- The wind dropped out in the evenings. On 9 Sep wind fell from 16 GW at midnight to 2.0 GW by 20:00, and gas plant rose from 2.4 GW to 13.9 GW. On 11 Sep the same: 14.1 GW at midnight to 2.3 GW at 20:00, gas to 13.1 GW. 10 Sep ran the other way (3 GW overnight, 12 to 14 GW by evening), which fits its lower peak of 47.5p (confirmed by data) Elexon FUELHH 9 to 11 Sep
- Nuclear and LNG. Five nuclear units (2,345 MW) off; "no cargoes booked into UK terminals through 16 September; storage at 49% with Rough empty" (confirmed by source, Catalyst 10 Sep).
- Even with 15 GW of wind in the small hours of 9 Sep, London's lowest price was 21.4p. With gas at about 190p, any hour where some gas plant was still needed priced high (inference).
Wider context that week. On Tue 8 Sep NESO's balancing costs hit a record £35m in one day, as strong wind in the north had to be turned down and gas plant run in its place Energy Live News, 14 Sep 2026. That doesn't feed into Agile but is a good illustration of the week: plenty of wind, in the wrong place, with expensive gas filling in. Euronews marked six months of the Hormuz blockade on 8 Sep. Diesel set a US record on 11 Sep.
Confidence. High.
Gaps. No mainstream UK press piece on power prices these days found (search allowance ran out). The "highest gas price since Dec 2022" claim is unverified, as noted in the context section.