Forty-three consecutive days of UK pump-price rises finally stalled this week. Unleaded stands at 158.3p, diesel at 191.5p — the highest diesel figure since 2022 and a near-record 33p gap between the two grades. The cause is not a refinery in Fawley or a storm in the North Sea. It’s a 21-mile-wide seaway between Iran and Oman that, since the morning of 28 February 2026, has been effectively closed to commercial shipping.
Why one strait matters so much
The Strait of Hormuz connects the Persian Gulf — home to the world’s largest concentration of oil and gas export terminals — with the Gulf of Oman and the open ocean. Roughly 20% of global crude supplypasses through it every day: 17-20 million barrels, loaded at terminals in Saudi Arabia, Iraq, Kuwait, the UAE and Qatar, bound for refineries in Europe, India, China, Japan and Korea.
When US and Israeli strikes targeted Iranian naval assets on 28 February, Tehran declared the strait unsafe and began intermittent blockade operations. Insurance rates for tanker passage quadrupled within a week; several shipping majors suspended transits entirely. The physical oil is still in the ground — but a meaningful fraction of the world’s daily supply is locked behind a bottleneck no one wants to test.
From the Gulf to your forecourt
The chain from a closed strait to your local Esso runs in five steps, each adding a few days of lag:
- Brent crude spikes. The global benchmark jumped from $72 in late February to a peak of $128 on 2 April — a 78% rise in five weeks. It sits at roughly $95 today as the market absorbs the shock.
- Refinery feedstock gets dearer. European refineries — Rotterdam, Antwerp, Fawley — pay the Brent-linked price for their crude. A $25 rise in Brent translates to about 12p/L of added wholesale cost.
- UK rack prices follow within days. The “rack price” — the wholesale figure paid by retailers — tracks Brent within 3-5 business days under normal conditions. Under a supply shock it’s faster.
- Pump prices follow, unevenly. Supermarkets reprice within 24-48 hours. Independents and motorway services lag by up to a week. This is why your local Tesco might be 5p cheaper than the Shell three miles away — same rack price, different adjustment speed.
- The pound adds a second layer. Crude is traded in dollars. Sterling has weakened against the dollar as the Middle East conflict drives a flight-to-safety rally in USD, amplifying the Brent rise by an extra 2-3p/L.
Why diesel went up harder
Since 28 February, diesel pump prices have risen roughly 39p/L while unleaded has risen about 20p/L — diesel taking the impact twice as hard. Three reasons:
- Europe imports more diesel than petrol from the Gulf. UK and European refineries run a “gasoline surplus” that’s offset by diesel imports — a lot of which move through the Strait of Hormuz in refined product tankers.
- Diesel’s refinery yield is less flexible. You can nudge a refinery towards more petrol or more diesel, but not by much. When demand for diesel outstrips what the gasoline-optimised European refineries produce, the shortfall has to come from imports or a wider price to attract them.
- Heating oil shares a supply chain with diesel. Some of the same refinery streams produce both. A cold European spring kept heating-oil demand elevated through March, tightening diesel availability just as imports were disrupted.
Our piece on why diesel is 33p more expensive than petrol goes deeper on this geometry.
What happens next
Three scenarios dominate the forecast space right now:
- Strait reopens in Q2. If diplomatic de-escalation lands in May-June, Brent eases towards $85, wholesale follows, and UK pumps give back 8-12p by mid-summer. EIA’s base case.
- Prolonged closure through summer. Shipping insurance stays elevated, OPEC releases emergency barrels at a slower pace than loss. Brent rangebound at $100-115, pumps stay near current levels.
- Escalation. A direct tanker incident or a second-order effect on Saudi terminals tips Brent above $140. Pumps add another 10-15p. Government may accelerate the September duty rise conversation.
What drivers can do
Not much about the Strait of Hormuz. Plenty about which forecourt you pick. During a supply shock the variance between stations widens — the retailer lag story above means the gap between the cheapest and dearest forecourt within a five-mile radius is often 15p+ right now, up from a typical 8-10p.
A postcode search will tell you which stations in your area have already repriced and which are still on last week’s numbers. In a volatile market, the difference over a year of commuting is significant.
Read today’s FuelHawk forecast →
The cheapest unleaded petrol in the UK →
Today’s UK national average →
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