The incident occurred just after 8.20am on Thursday, August 6, and led to the closure of the A1005. A London Ambulance Service spokesman said: "We treated a patient and took him to a local hospital as a priority." There are major delays on the M25 (Image: Google Maps)The collision caused very heavy traffic on a section of the M25 towards Potters Bar and has led to diversions on the 313 bus route. Transport for London confirmed there is a diversion in both directions.