An unidentified object thrown off a motorway bridge hit a lorry and cracked its windscreen.

At about 10.30am on March 2 a lorry was driving on the M25 just past junction 8, near Leatherhead, on the anti clockwise carriageway when it passed under the footbridge which crosses the motorway.

The driver heard a loud bang on the windscreen and realised a glass dent had appeared and the windscreen glass had cracked.

The driver saw two people standing on the bridge before the incident and was shaken but not injured, according to Surrey Police.

Officers are now appealing for information and reminding potential offenders they may face jail if caught throwing objects from bridges.

Acting Detective Inspector Tony Giles said: “It is extremely dangerous to throw objects from bridges into the paths of on-coming traffic.

“On this occasion the driver was able to keep control of the lorry but a distraction of this magnitude could have easily caused him to lose control and collide with another vehicle on the busy motorway.

"The consequences could have been much worse and, as a result of one mindless act, the culprits could have been facing charges of manslaughter or even murder.

“In 2003 lorry driver Michael Little died after a teenager threw a brick through his cab window. That teenager was sent to prison for six years.

“We are very keen to trace those seen on the motorway bridge prior to this incident. The M25 is a very busy motorway and I am confident someone must have seen these people.

"We would like to hear from any witnesses to this incident or anyone who remembers seeing two people on or around the bridge and can provide any further information about their identity.

“We would also like to hear from anyone else who may have been victim to or witnessed any similar incidents that day.”

Anyone with information should contact Surrey Police on 0845 125 2222 or Crimestoppers, anonymously, on 0800 555 111.