The M40 southbound was closed after a police incident just before junction 1a for the M25, with drivers heading towards London held up on Monday morning.
The closure was first reported at around 8.10am on Monday, November 9. Traffic caught inside the closure was released from the rear, but the road remained shut for much of the morning.
The M40 is the main route between London and Oxford and Birmingham, and the closure sits at the London end of the motorway, where it meets the M25 at junction 1a. Drivers heading into the capital from the west faced delays, with traffic building on the approach to the closure.
Thames Valley Police confirmed the closure was caused by a crash involving four vehicles this morning. Delays reached about 90 minutes, with four miles of congestion, and later became severe, with congestion stretching back before junction 3 and routes through Beaconsfield and Gerrards Cross affected. Thames Valley Police confirmed it was a minor injury incident. National Highways later confirmed the road had reopened, and traffic sensors indicated traffic was easing.
Drivers were advised to avoid the area while the closure was in place. The A40 through High Wycombe was the usual alternative route into London from the west, though it was busier than usual while the motorway was shut.
The closure comes on a foggy morning for the capital — a yellow fog warning is in force across Greater London, with visibility as low as 50 metres in places.
Live coverage has now ended.
The road has reopened and traffic is easing. Updated: 09 November 2026
