London's new-build market, long considered the bellwether of premium UK housing, is now flashing warning signs that have been building for years. New-build prices in the capital have fallen in real terms, with several boroughs reporting declines of between 3% and 8% over the past 12 months, according to industry estimates. This is not a minor correction. It represents a fundamental repricing of a segment that developers and investors have relied upon to underpin viability appraisals, land values, and the entire logic of high-density regeneration schemes across zones one to three.