ONS data show London's population fell by about 27,000 to roughly 9.1 million at
mid-2025, reversing a record set the prior year. This is the first decline since
the 1980s outside the pandemic outflow, and London was the only English region
to shrink last year. ONS attributes the loss mainly to net migration to other
parts of the UK as high housing and living costs push some residents out. The
city had dipped in 2020–21 during COVID but recovered to a record high over the
next three years before this reversal.
