Britain on Tuesday ramped up its response to the escalating coronavirus outbreak after the government imposed unprecedented peacetime measures prompted by scientific advice that infections and deaths would spiral without drastic action.

More firms sent staff to work from home and public transport emptied after the government called for an end to "non-essential" social contact and unnecessary travel, as confirmed cases climbed to 1,950, with 69 deaths. The government's chief scientific adviser Patrick Vallance said it was "reasonable" to estimate that 55,000 people could have COVID-19, based on an expected death rate of one in 1,000 cases.

"If we can get numbers down to 20,000 and below, that's a good outcome in terms of where we would hope to get with this outbreak," he told a parliamentary health committee. "But that's still horrible. It's still an enormous number of deaths and an enormous pressure on the health service."

In new developments:

Britons were told only to travel abroad if absolutely necessary for the next 30 days, to avoid being stranded by border closures, flight cancellations and strict curfews.

the National Health Service in England said all non-urgent operations would be postponed from April 15 for at least three months, in a move designed to free up 30,000 beds.

Queen Elizabeth II moved to her Windsor Castle residence west of London a week early, and said several large public events, including royal garden parties, will be postponed or cancelled.

the Church of England's most senior cleric, Archbishop of Canterbury Justin Welby, said public worship was "suspended until further notice", but weddings and funerals can still be held.

The moves came as tougher emergency restrictions on social contacts are expected to be introduced, including forcing people with serious health conditions to stay at home for three months. Prime Minister Boris Johnson has faced criticism for his approach to the pandemic, which had involved holding off on imposing the strict measures seen in other countries.

But he stepped up the response on Monday after scientists warned hundreds of thousands could die in Britain if there was only a focus on delaying and slowing infections.

'Intensive intervention'

Thirty members of Imperial College London's COVID-19 response team concluded in a paper that suppression was "the preferred policy option" to curb the spread of the virus. It would require "a combination of social distancing of the entire population, home isolation of cases and household quarantine of their family members".

"This type of intensive intervention package... will need to be maintained until a vaccine becomes available (potentially 18 months or more)," the report stated.

They predicted transmission would "quickly rebound if interventions are relaxed", it added. The study's lead author, epidemiologist Neil Ferguson, is advising the British government's Scientific Advisory Group for Emergencies, which is helping coordinate its COVID-19 response.

He said he had also shared the projections with US President Donald Trump's administration last week and sent it an early copy of the report over the weekend. Ferguson said the government had "no other option" but to implement new measures because modelling from new Italian data indicated 81 percent of Britons and Americans would be infected.

Some 510,000 would die in the UK and 2.2 million in the US, peaking after three months. Mitigation policies would only halve that number and healthcare systems would still be overloaded. The sobering assessment saw London and Washington both announce stringent new social distancing measures on Monday.

'Crippling blow'

The latest measures sparked concern about the impact on business, especially in the hospitality industry, amid fears of an extensive economic fall-out from the outbreak. Fashion chain Laura Ashley filed for administration, putting up to 2,700 jobs at risk, and car giant Nissan announced a halt in production at its Sunderland factory because of falling demand.

Meanwhile, the British Beer and Pub Association warned thousands of jobs would be lost if pubs went to the wall without government intervention. Arts groups said they faced a "crippling blow" if audiences stayed away. The Tate museums and galleries announced their closure until May 1.

All events in London's Trafalgar Square, including upcoming celebrations for St George's Day, Vaisakhi and Eid, were cancelled until further notice, Mayor Sadiq Khan said. Controversially, schools remain open.

But the government, which has promised a £30-billion ($36-billion) package of support for affected individuals and businesses, maintains it is guided by the latest science.