The Office for National Statistics will publish its first quarterly estimate of UK GDP for January-March 2026 on Wednesday 14 May at 7am, in what would normally be a routine data release but has become one of the most hotly contested numbers in British economics. Most City forecasters expect growth of 0.5% to 0.6%, which would be the fastest quarterly expansion since early 2025 and a sharp acceleration from the unrevised 0.1% recorded in Q4 2025. But behind closed doors, the Bank of England, the ONS itself, and the official statistics regulator have all signalled that the figure may be wrong.
Why Wednesday’s number matters more than usual
February 2026 alone saw monthly GDP rise by 0.5%, the biggest monthly increase in over two years according to the ONS February 2026 bulletin. Services grew 0.5%, production 0.5% and construction 1.0% in February. The three-month rolling growth to February was 0.5%, with services contributing the bulk. On the surface, that produces an encouraging headline. The problem, as the BoE has flagged in its most recent Monetary Policy Report, is that the same pattern has repeated for four consecutive years: between 2022 and 2025, UK GDP averaged 0.5% in Q1, 0.3% in Q2, then collapsed to effectively zero in the second half. Each strong start gave way to disappointing autumns. Each year, the seasonal adjustment failed to flag the borrowing.
The BoE’s concern: a statistical illusion
The Bank of England’s chief economist Huw Pill, the lone dissenter calling for a rate hike in the 30 April 2026 8-1 vote that held Bank Rate at 3.75%, has been at the forefront of internal scepticism. According to Bloomberg’s reporting, the BoE has noted privately that Q1 growth of 0.5% would be “higher than survey indicators suggest”, and that the data follows “a pattern of unusually strong Q1 readings in recent years.” The Monetary Policy Committee next meets on 18 June 2026, with two scheduled rate decisions before year-end on 30 July and 17 September.
The ONS concession: errors and a methodology rethink
Compounding the unease, the ONS has admitted it found errors in the price indices it uses to calculate GDP, pausing publication of affected data and warning of potential revisions stretching back to 2022. The statistics regulator has separately pressured the ONS to revisit its seasonal adjustment methodology after outside experts identified significant limitations. In response, the ONS will begin publishing non-seasonally adjusted GDP figures from Wednesday’s release for the first time — a remarkable concession that the headline number alone could mislead.
The Iran war timing problem
The conflict in the Middle East began on 28 February 2026, meaning most of Q1 predates the full economic impact. CPI inflation was already running at 3.3% in March and is projected by the BoE to be 3.1% in Q2, 3.3% in Q3, and to “rise somewhat further in Q4.” The Bank’s own scenario analysis puts peak inflation between 3.5% and 6.2% depending on the duration of the energy shock. In the most severe scenario, rates could rise to 5.25% by 2027 — a tightening that would batter the mortgage market, business investment and consumer spending simultaneously.
The OBR forecast and the Treasury survey
The Office for Budget Responsibility’s March 2026 Economic and Fiscal Outlook forecast GDP growth of 1.1% in 2026 and 1.6% in 2027. The Treasury’s April 2026 survey of independent forecasts showed an average of 0.6% for 2026 and 1.1% for 2027 — far below the OBR. The gap matters because public spending plans assume the OBR is broadly right; if the average forecaster is closer, fiscal headroom evaporates.
What to watch on Wednesday
Three numbers to focus on at 7am, 14 May: the quarterly GDP print (consensus 0.5%); the March monthly figure (revisions to February’s strong 0.5% will reveal whether the rebound has held); and — for the first time in a major UK GDP release — the non-seasonally adjusted comparison. If the seasonally-adjusted number is markedly higher than the non-adjusted one, the ONS will have validated the BoE’s quiet warning that Q1 strength is being borrowed, not earned. The next monthly GDP release follows on 13 June, the day before the next ONS quarterly national accounts on 30 June.
Reporting from London on the eve of one of the most consequential UK GDP prints since the pandemic.
