Commuters are facing long delays after a “serious” accident at a major motorway junction. Traffic is being held on the M20 at Swanley following the crash, which happened just before 7am between junction one for the M25 and junction 3 for the M26. Three vehicles are believed to have been involved in the collision. All traffic is being held on the main carriageway in both directions while the coast-bound entry slip-road remains blocked coming from the clockwise M25. Vehicles are reported to be using the London-bound slip-roads to divert around the accident scene. Traffic heading to London is que…