The government is exasperated at Channel 4's reluctance to move out of London and is considering a change in law to force it to relocate, BuzzFeed News understands.
Ministers are heaping pressure on the broadcaster to come up with concrete plans by the new year, with culture secretary Karen Bradley expected to hold talks with new chief executive Alex Mahon within weeks.
Government officials are understood to have pointed to a private member's bill, currently going through parliament, that could be used as a vehicle for forcing a relocation if the network fails to comply.
Bradley has said that Channel 4, as a publicly owned broadcaster, should "do more to support economic growth and provide for audiences outside of London".
Liverpool, Birmingham, Sheffield, and Bristol are among the cities that have expressed an interest in hosting the broadcaster, following a government consultation earlier this year.
But government insiders are frustrated at the response from Channel 4. One Whitehall source told us: "It is just very well-paid TV people who seem to be horrified at the idea of living anywhere apart from London. If they don’t come round to it, we will look at changing the law."
The source suggested the broadcaster's new management team have until January to "get on board".
Channel 4 warned in March that a full-blown relocation would be "highly damaging", while its former chief executive David Abraham claimed the move would "destroy" the channel.
Bradley appeared to offer an olive branch in September, saying that not all the broadcaster's operations needed to move from London. "Relocation may not mean the whole business, but I am clear that Channel 4 must have a major presence outside London, and potentially increase commissioning," she said.
A private member's bill from Tory MP Jack Brereton could be used as the vehicle for the law change. In October, he told the Commons: "Being in public ownership means that Channel 4 has a responsibility to the nation, not just in the innovative and boundary-probing programming that it rightly produces, but in the way in which it is organised and run.
"Truly, it must be operated for the benefit of all parts of our country, throughout all the nations and regions that make up the UK."
His bill requiring Channel 4 to relocate its headquarters outside London is due to have its second reading in October 2018.
A Channel 4 spokesperson said: "We are proud of our leadership on diversity and the substantial contribution we make to the nations and regions and we want to grow this further and give even greater support to creative talent across the UK.
"We are working closely with government to ensure we support the important principles of regional representation and deliver our remit."