“5G depends heavily on 4G infrastructure.” says Matthew Howett, of Assembly Research. “Switching our Huawei for 5G will mean replacing some 4G equipment which would need to be added to that cost.” Assembly estimated the total economic cost would be £7bn.

Matthew Howett, an analyst at Assembly Research, said: “BT will want to keep hold of Openreach rather than divest fully given the huge advantage of it being an anchor tenant for their broadband service.”

Matthew Howett, an analyst at Assembly, said a merger of fixed line and a mobile firm was more likely to be approved by competition regulators than a merger of two mobile firms.

"If we end up in a situation where worldwide, 850m children start to receive lessons virtually for an extended period of time, then networks might want to start prioritising video traffic over gaming traffic," said Matthew Howett, principal analyst at Assembly.

Analysts warned that state control of Openreach could bankrupt rival cable providers such as Virgin Media, whose cable network covers half the UK, as well as TalkTalk and smaller challengers.

“What would the poin of their existence be?” said Matthew Howett, an analyst at Assembly. “They would fall away overnight. It would add to the lunacy.”

Some commentators have argued that Openreach needs a shake-up regardless. Customer satisfaction is low and there have been long delays launching faster broadband in the UK. Only around 10pc of the UK has access to full-fibre despite years of promises.

Matthew Howett, the principal analyst at Assembly Research, pointed to a similar approach in Australia which has caused delays for customers.

“Only one other country in the world has come close to going down this route, and for a good reason – it’s hard, expensive and fraught with difficulty,” he said. “Australia’s NNB is years late, massively over budget and offering speeds and technology a fraction of the original political intention.”