A 3% oil shock cost sterling about half a cent

Back out the 3% and Brent was near $104.85 before the pipeline news, so the closure is worth about $3.15 a barrel ^[1]. The same exercise on sterling puts the prior print near $1.3528, half a cent above where the pound ended the day ^[2]. For every 1% Brent added, the currency gave up 0.13% ^[3].

The oil market's own forward pricing moved less than the spot headline suggests. Pricing on crude setting a new all-time high by December 31 went from 14% to 15.5% ^[14], a rise of about 11% in the implied odds ^[5] off a level that still puts roughly five and a half to one against a record by year end ^[4]. Traders who expected the bypass to stay shut into December would presumably have paid more than 15.5 cents for that outcome.

There was plenty else pressing on the pound. By the same account, markets were pricing a higher chance the Fed hikes around September 16 while the Bank of England was expected to hold ^[7]. The ECB had already raised ^[8]. British bond yields were at multi-decade highs, and July GDP came in at 0.4% against forecasts of essentially flat output ^[11][10]. Commerzbank's analysts, in that report, see markets overestimating the pace of future UK rate hikes; on their reading the pound has further to fall as traders recalibrate ^[9].

Both accounts here come from cryptobriefing.com, and the second credits a Reuters report for the dollar index reaching a two-week high ^[4]. Neither outlet cited a named official.

I'd put most of that half cent on the rate path, with the pipeline supplying the timing rather than the size. The counter-case is a real one: oil is invoiced in dollars, Britain is a net energy importer, and a higher crude price worsens its trade balance directly ^[5][6]. If Brent gives back the $3.15 ^[1] and sterling stays near $1.3474 ^[1], the energy explanation was thin. If crude holds and the pound keeps sliding through the Fed meeting, the import bill mattered more than the differential.

The distinction matters for the Bank of England. According to the same account, it faces elevated energy costs feeding consumer prices and a narrower range of policy options ^[12]. Roughly one-fifth of the world's oil supply passes through the Strait of Hormuz, and the closure has temporarily removed the route built to get around it ^[13].