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WFN QUICK BRIEF · UNDER 1 MIN
The short version
MODE 2 OF 2
What the source establishes
In May 2021, ONS explained how unusually weak activity and price observations during the first pandemic year affected subsequent twelve-month comparisons. Its inflation discussion focused on fuel-price movements dropping out of the annual comparison. This is a dated methodological example, not a claim about the latest UK release. ONS Chief Economist — Beware Base Effects, 19 May 2021 ↗
What the distinction changes
Here is an explicitly illustrative calculation. An index rising from 100 to 110 records 10% annual inflation. A year later, a level of 112 compared with 110 records about 1.82%. Prices are still higher, even though the annual rate is much lower. These values are arithmetic examples, not observed CPI data.
Questions for the next review
Read the official component contributions, the index levels and the appropriate monthly measures alongside the annual headline. Preserve seasonal-adjustment labels. Avoid describing slower inflation as cheaper living costs unless the relevant price level actually fell.
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WFN STORY COMPASS
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EDITORIAL ILLUSTRATIONWFN EDITION · 15 OCTOBER 2026
Editorial noteSource-based explanation with original WFN analysis. Historical records retain their original periods. Numerical examples are labelled as illustrative, not observed market data. AI-generated conceptual illustration; it does not document an actual event or product interface.
WFN REALITY LEDGER
What is on the record?
Primary-source explainer
Primary-source explainer; examples are explicitly illustrative
Primary record / reference periodHistorical ONS explanation published 19 May 2021
The cited material establishes the documented method or historical record. WFN analysis and illustrative calculations are labelled separately.
ONS’s explanation shows why annual inflation depends on last year’s comparison. Falling inflation and falling prices are separate statements.
01 · VERIFIED RECORD
What the source establishes
In May 2021, ONS explained how unusually weak activity and price observations during the first pandemic year affected subsequent twelve-month comparisons. Its inflation discussion focused on fuel-price movements dropping out of the annual comparison. This is a dated methodological example, not a claim about the latest UK release. ONS Chief Economist — Beware Base Effects, 19 May 2021 ↗
The essential distinction is between a price level and its rate of change over a selected interval. An annual rate compares the current index with the corresponding index twelve months earlier; changing that comparison point can affect the result. ONS Chief Economist — Beware Base Effects, 19 May 2021 ↗
02 · WFN EDITORIAL ANALYSIS
What the distinction changes
Here is an explicitly illustrative calculation. An index rising from 100 to 110 records 10% annual inflation. A year later, a level of 112 compared with 110 records about 1.82%. Prices are still higher, even though the annual rate is much lower. These values are arithmetic examples, not observed CPI data.
For FX reporting, the implication is to ask what caused a change in the annual figure. A base effect may explain part of the movement without answering whether recent price pressure has eased. Equally, the presence of a base effect does not by itself make an inflation release irrelevant.
03 · WHAT TO CHECK NEXT
Questions for the next review
Read the official component contributions, the index levels and the appropriate monthly measures alongside the annual headline. Preserve seasonal-adjustment labels. Avoid describing slower inflation as cheaper living costs unless the relevant price level actually fell.
