Britain had an estimated 442,000 sterling millionaires in 2025, down from 1.07 million in 2021 after four straight annual declines, according to the Adam Smith Institute’s tracker.
A 7% drop from 2024 capped the slide as higher interest rates, weak confidence, low household savings and falling real values of pensions and prime London property pushed fewer residents above the £1 million threshold.
The institute also pointed to emigration by wealthy residents and would-be arrivals after the non-dom regime ended in April 2025 and the UK remained without a dedicated investor visa following the 2022 closure of Tier 1.
The figures land eight days into Chancellor John Healey’s tenure, with no Budget due before autumn; advisers say Labour’s pledge not to raise the main income-tax, VAT or employee-NI rates could shift attention to capital and asset taxes.
The estimate is modeled rather than counted, but its direction broadly matches a 19% real fall in aggregate household net worth between 2021 and 2023 cited from Resolution Foundation analysis.