Transport union chief Manuel Cortes has unleashed fresh calls for rail renationalisation following revelations the Southern Rail parent company made record profits in the face of immense failures of the rail network.

London Mayor Sadiq Khan has also hit out at the Tory Government’s dealing with the franchise.

Go-Ahead, which operates the Southern Rail network, has made £100m in profits – an increase of 26.8 per cent on the previous year. The announcement comes only a day after the rail operator was awarded a £20m subsidy from Transport Secretary Chris Grayling – designed to help the company “get to grips” with its problems.

Cortes, who is general secretary of TSSA, said Southern services were “dangerously overstrained” after cuts to services and staff, even while passenger numbers were increasing.

“All you need to know about the topsy turvy world of Britain’s privatised railroads are contained in this announcement that Go-ahead have met their strategic and financial targets and made £100million in profit. Delivering passengers to and from their destinations on time, in comfort or even safely has very clearly not been priority.

“Southern is the largest franchise in the network and is now dangerously overstrained because Go-ahead have made their money by cutting services, cutting trains, cutting staff and cutting safety standards whilst passenger numbers have been increasing. Running 270pc over capacity, passenger surveys show Southern has the unhappiest passengers in the country and the worst industrial relations.

“Never has the case for returning the rail franchises into public hands looked stronger. We need to end the gravy train for the privateers and bring back railways into the public control so they work in the interests of British passengers and taxpayers, with profits made here invested in rail upgrades and passenger services here.”

He condemnation was echoed by Sadiq Khan, who called on the government to speed up handing over the commuter lines to the control of Transport for London.

He went on to condemn the Conservatives for refusing his offer to send a specialist TfL team to the rail network to help solve its problems, saying the government has been “wholly inadequate”.

“Long suffering commuters across South London will be shocked to hear that Go-Ahead has announced soaring profits, less than 24 hours after Chris Grayling announced a £20 million taxpayers handout to prop up the franchise.

“The reaction to the cancellations, delays and poor service from both Southern and the Government has been wholly inadequate.

“Commuters will not understand why the Government rejected my offer to send a specialist TfL team in to Southern to sort this mess out for free and instead has rewarded a failing franchise with more money and more time.

“In addition to sorting out the mess, the Government should speed up handing over the commuter lines to TfL to ensure we give commuters the efficient and reliable rail service they deserve, while providing value for money.”

The news follow a series of strikes from rail worker over changes to staffing, as well as record numbers of delays and cancellations from the network which is widely regarded as the worst in the UK.