A rail provider has been forced to appoint a troubleshooter to arrest a sharp downturn in punctuality and reliability.

Southern Railway's punctuality in South London has dropped by almost 10 per cent in the last year while reliability has gone down too.

The provider, which operates some of the busiest lines in the capital, has appointed David Scorey as performance director and tasked him with the job of looking at why performance has declined and how to improve it.

A Southern spokesman said: "Lately it is fair to say that our performance has not been as good as we, or our passengers, expect. A range of factors have affected our daily punctuality including weather related issues and railway infrastructure failures, but also some areas where we have direct control over our own processes and equipment."

Mr Scorey added: "The complexity of our network and the sheer volume of trains we run every day means that when there are problems, there’s quickly a knock-on effect to the performance of other trains and that has a significant effect on overall punctuality.

"I will be working with Southern’s own performance team and with Network Rail colleagues to ensure there is even more focus on bringing our performance up to the levels we aim to deliver and our passengers rightly expect."

Mr Scorey, previously in charge major projects at Southern, started his job on Monday but even before he took the reigns Carshalton and Wallington MP Tom Brake met him to put across the views of people in Sutton.

He said: "It was a useful meeting. He acknowledged that Southern has seen a deterioration in performance and a sharper deterioration in the last three months.

"This is a key issue - when people are paying for a service they aren't getting it sticks in their throats."

Mr Brake asked about issues raised with him by constituents. These included the accessibility for disabled people at Carshalton and Carshalton Beeches stations, which he said is not set to change, and the lack of detailed information when trains are delayed which he said Southern is looking into.