Union leaders are calling for two railway services to be taken into public ownership, saying it would lead to “significant” savings.

Aslef and the Rail, Maritime and Transport union (RMT) said taking London’s Elizabeth line and London Overground under public control would improve services.

RMT general secretary Mick Lynch and Aslef leader Mick Whelan said in a letter to London’s Mayor Sadiq Khan: “Privatisation has been a costly inefficient failure”, adding that the government’s forthcoming legislation makes public ownership the default option for the rest of the country’s railways.

The union leaders highlighted what they believe would be the financial and service-related benefits of public ownership.

“There will be significant savings to government. Public ownership represents an opportunity to improve passenger rail services by removing the commercially driven focus on individual operators’ profit,” the letter said.

“London would not only share the same policy direction as the national government, but public ownership would make it significantly easier to create the kind of governance structures that would enable greater devolution to London.”