UK inflation accelerated further ahead of the central bank's rate decision, as the energy price shock continues to feed through to household bills and consumer costs, squeezing the Bank of England's room to keep policy on hold.

Data from the Office for National Statistics released on 16 September showed the consumer price index rose 3.1% year-on-year in August, up from 2.9% in July and marking the highest level since March this year, in line with market expectations. Higher petrol and diesel prices were the main driver, while rising household energy bills added further upward pressure to the overall inflation figure.

The Bank of England's Monetary Policy Committee meets on Thursday, with markets broadly expecting the benchmark rate to remain at 3.75%. However, if the energy shock continues to lift inflation, traders have begun pricing in the possibility of a renewed rate hike as early as November. Following the inflation release, market pricing for a hike this week actually fell from 35% to 25%, indicating that investors still see the central bank as most likely to stay on hold in the near term.

Meanwhile, higher inflation is also adding to fiscal pressure on the government. The recent sharp rise in gilt yields has been estimated to have shrunk the government's fiscal headroom by more than half, further limiting the policy flexibility available for the October Budget.

Energy Prices Take Centre Stage as Key Driver of Inflation Uptick

The August acceleration in inflation was driven primarily by energy costs. The ONS noted that sharp increases in petrol and diesel prices were the leading contributor to the monthly CPI rise, with airfares and producer output prices also adding to the increase, while household energy bills provided further support.

Ofgem, the UK energy regulator, raised the household energy price cap by 13% in early July, directly lifting electricity and gas costs. Meanwhile, Brent crude has recently broken back above $100 per barrel, and Ofgem has announced plans to raise the energy price cap again in October, suggesting that energy prices will continue to underpin inflation in the coming months.

David Rees, global head of economics at Schroders, said UK inflation is likely to rise further in the months ahead, as energy, industrial goods and food costs continue to pass through to end consumers.

Market expectations currently point to UK CPI potentially reaching or exceeding 4% early next year — double the Bank of England's 2% target.

Core Inflation Steady, Still Giving the Bank Room to Wait

However, the rise in headline inflation does not mean price pressures have become broadly entrenched. Core inflation, which strips out energy and food, held steady at 2.6% in August, while services inflation — a key focus for the Bank of England — remained stable at 3.4%.

This suggests that the current inflation uptick remains concentrated in external factors such as energy, and has not yet clearly evolved into broader domestic price pressure. Francesco Pesole, strategist at ING, noted there is still no evidence of inflation pressures spreading beyond the energy sector, which provides support for the dovish camp within the central bank.

The cooling labour market also gives the Bank some latitude to delay action. Official data released on Tuesday showed private sector wage growth, excluding bonuses, stood at 2.8% for the three months to July, down from 2.9% previously, while overall weekly earnings growth was just 2.9%.

David Rees pointed out that current wage trends have not repeated the wage-price spiral seen in 2022. In other words, as long as the energy shock does not further accelerate wage and services price growth, the Bank still has reason to keep observing rather than respond to energy prices with an immediate rate rise.

Bank's Watch-and-Wait Strategy Faces Growing Test

The problem is that the duration and transmission of the energy shock is becoming more consequential. The Bank of England has held rates unchanged since February when the Middle East conflict erupted, awaiting more evidence on whether inflation would persist. The MPC's vote of 6-3 to hold at its last meeting in July also signals notable divisions within the policymaking committee.

Yael Selfin, chief economist at KPMG, said rising energy costs could test the Bank of England's wait-and-see approach. She argued that the current price increases do not appear to be driven by an overheating economy or second-round effects, but if inflation persists, the Bank could deliver a precautionary rate hike in November. Until then, the energy price shock remains an external factor that the central bank cannot directly control.

Andrew Goodwin, UK economist at Oxford Economics, also noted that August data has yet to show second-round effects, but the scale of external price pressures has become so pronounced that the MPC is increasingly likely to be compelled into action.

Inflation and rate pressures are also feeding through to the fiscal side. Elevated gilt yields are eroding government fiscal headroom, while cost-of-living pressures are intensifying political demands for the government to ease the burden on households. Chancellor John Healey said the Middle East conflict is pushing up inflation globally, and the government has taken advance measures to help families and businesses. Shadow Chancellor Andrew Griffith criticised the situation, saying that 3.1% inflation means households are bearing higher living costs.

As such, the Bank of England is still widely expected to hold rates steady on Thursday, but as energy prices continue to feed into inflation data, the tolerance for allowing inflation to drift higher is narrowing. The key question now is whether core inflation, services prices and wage growth can remain stable, which will determine whether the Bank can sustain its wait-and-see stance.