The first guests have checked into quarantine hotels as tougher rules for international arrivals come into force.
UK and Irish nationals and UK residents returning to England from 33 “red list” countries, hotspots with Covid-19 variants in circulation, are required to quarantine in hotels for 11 nights.
The rule applies to people returning to Scotland from any destination.
Passengers arriving at London’s Heathrow Airport were escorted by security personnel to coaches which took them to nearby hotels.
A handful of people pulled up to the Radisson Blu Edwardian hotel shortly before 9am.
One woman, who had flown in from Zambia, said: “I’m not happy, but you have to do it.”
Health Secretary Matt Hancock said the system has been operating “smoothly” since it came into force at 4am on Monday.
Asked on Times Radio how quarantine hotel-bound passengers are being prevented from mixing with other arrivals in airports, he said: “All of this has been clearly set out, and I’m glad to say that, as of 6.30am when I got my latest update, this is working smoothly.
“We’ve been working with the airports and the Border Force to make sure that everybody knows (how it works).
“We have had to put this in place rapidly, I make no apologies for that, and we’ve been working with Heathrow and others.”
Pressed on how “red list” passengers are being kept away from others, Mr Hancock added: “You go down a separate channel at the gates and, once you’ve been through the gates, which are manned by the Border Force, there is then a security operation supported by the police so that people are gathered, go and pick up their luggage and then go to the hotels.
“So that’s all in train; there was a walkthrough of it yesterday and obviously it has been in place since four o’clock this morning.”
People required to enter the quarantine hotel programme must enter England or Scotland through a designated port and have pre-booked a package to stay at one of the Government’s managed facilities.
No international flights are operating to Wales or Northern Ireland.
The Government has struck deals with 16 hotels so far, providing 4,963 rooms, with a further 58,000 rooms currently on stand-by, the Department of Health and Social Care (DHSC) said.
People must quarantine in the hotel room but exceptions allowing them to leave include the need for urgent medical assistance, to exercise or attend the funeral of a close family member.
The regulations state that leaving for these exceptional reasons should only happen if the person “has been given prior permission by a person authorised by the secretary of state for this purpose”.
People may only arrive into Heathrow Airport, Gatwick Airport, London City Airport, Birmingham Airport, Farnborough Airport or any military airfield or port, according to the legislation.
Passengers arriving in England face fines of up to £10,000 for failing to quarantine, and those who lie on their passenger locator forms face up to 10 years in jail, Mr Hancock announced last week.
The cost for a quarantine hotel stay is £1,750 for a single adult.
On Saturday, Heathrow Airport said “significant gaps” remain in the hotel quarantine plan and a spokeswoman said it is yet to receive the “necessary reassurances” from the Government.
On Sunday night, the Heathrow spokeswoman said: “We have been working hard with the Government to support the successful implementation of the managed quarantine policy from Monday.
“Good progress has been made to address a number of issues.
“Queues at the border in recent days have been almost five hours and this is totally unacceptable.
“Border Force today have given us assurance that they will have resource and effective processes at the border to avoid compromising the safety of passengers and those working at the airport, which could necessitate the suspension of some arriving flights.”
People returning to England who have not visited a “red list” country must quarantine for 10 days at home and complete two mandatory Covid-19 tests on the second and eighth day after arriving.