Entry to the M25 towards Heathrow is blocked at South Mimms after a lorry overturned on the slip road.

Police have blocked access to the westbound carriageway while they deal with the 16-wheel Conway truck, which rolled off the road and through a metal barrier shortly before 1.30pm.

The driver escaped with minor leg injuries when the vehicle crashed but queues are building up to the closure.

The Highways Agency is recommending drivers wishing to travel westbound take the eastbound carriageway and turnaround at Potters Bar.

Elliot Samson was driving past and witnessed the scene a short time ago.

He told the Times Series there were still two fire trucks, a highways incident vehicle and police cars at the scene.

An East of England Ambulance Service spokesman said in a statement: “We were called at 1.25pm, dispatching a rapid response vehicle, ambulance and duty officer.

“A lorry had overturned and a man in his 50s suffered a leg injury. He was conveyed to Barnet General where his condition isn’t serious.”