A track where a train derailed in Wimbledon was “not inspected or maintained for many years” a report has found.

The train from Basingstoke to London Waterloo derailed shortly after departing from Wimbledon station on November 6, leaving four people injured. Hundreds more were forced to evacuate.

A report by the Rail Accident Investigation Branch (RAIB) said the derailment occurred on a short section of track that provides the link between the main line, which is owned and maintained by Network Rail and the District Line.

The report said the cause of the accident was because the distance between the rails, known as the track gauge, was greater than the distance needed to restrain the wheelset.

The report said that London Underground and Network Rail were responsible for inspecting their bits of track but, while patrollers may have been checking the area immediately beyond their boundary, the gap of 120 metres between patrolled areas meant that a significant stretch of track was missed from inspections.

According to RAIB, neither London Underground nor Network Rail were able to provide reasons why the boundary was different in the patrol diagrams and why these did not match the location agreed between the two organisations in 1994.

In the report it states that: “The consequence of this oversight was that the track was not being inspected or maintained for many years and so degraded into an unsafe condition.”

The RAIB said there was confusion between London Underground and Network Rail as to who was responsible.