Thousands of vehicles remain trapped on the clockwise carriage of the M25 between junction 6 near to Clackett Lane services and junction 5 the A21/M26 interchange in Kent this evening.   An overbridge on London Road in Westerham as also been closed whilst officers carry out their investigation. Officers from Kent Police were called along with Paramedic and the Kent Sussex and Surrey Air ambulance to the hard shoulder of five-lane carriageway.   All Lanes on the M25 were closed at one point to allow the air ambulance to land. The pedestrian was treated at the scene before being airlifted to a London hospital.< Scene of crime officers can also be seen on the overbridge taking pictures a yellow high vis coat can also be seen on the carriageway. A spokesman for National Highways said: Emergency services including Kent Police are in attendance. National Highways Traffic Officers are also on the scene to assist with traffic management. Due to a planned roadworks closure on the strategic diversion route on the A25, traffic is currently being diverted via local routes. There is currently 4.5 miles of congestion on the approach to the closure with delays of 30 minutes above normal travel time.     A spokesman for  Kent Police said: “Officers were called at 7.40pm on Thursday 9 December 2021, to a location on the M25 where a pedestrian has fallen and suffered serious injuries. No vehicles were involved. The anti-clockwise carriageway is currently closed between junctions 6 and 5.   There are also delays on the clockwise carriageway. Officers and ambulance crews remain at the scene. The closure is likely to remain in place for a number of hours. More to follow