Network Rail contributed to South Western Railway's poor performance

The Office of Rail and Road has called on Network Rail to improve both planning and its procedures.

Findings include that the percentage of trains arriving on time dropped from 90.5 per cent in 2015/16 to 84.3 per cent in 2017/18.

The ORR said 68 per cent of the delay in 2017/18 was caused by Network Rail. This sparked the investigation by the ORR.

Graham Richards, director, railway planning and performance at ORR, said: '˜Passengers using South Western Railway have faced unacceptable disruption in recent months.

'˜When things go wrong, it is essential that Network Rail works efficiently to get back to normal service as quickly as possible.

'˜Our investigation found that Network Rail has not updated its processes and technology to keep pace with the changes on the route.

'˜We will be looking closely to ensure it addresses our findings.

'˜We acknowledge that the performance issues on SWR are not down to Network Rail alone, and we have therefore shared our findings with Michael Holden to inform his review.'

Contingency plans had not been updated since 2011. Network Rail has been taking longer to fix problems, the report added.