NationalHighways

M4 closed between Harrow and Heathrow after police incident, diversions in place

National Highways confirmed the M4 was closed in both directions between junction 3 (Harrow) and junction 4 (Heathrow) at 1:35 am on 9 September 2026 after a police‑led incident. Westbound traffic is diverted via the A312 and A40, while eastbound drivers follow a separate route. The agency says there were no significant delays.