Portugal has been moved to England's travel amber list, just weeks after Brits were told they could travel to the country without self-isolating.
The latest change in travel advice means people returning to the UK from Portugal will need to quarantine at home for 10 days when it comes into effect from 4am on Tuesday.
The news will come as a huge blow to the thousands of holidaymakers who flocked to Portugal when it was added to the green list on May 7 - the only viable major tourist destination on the list.
But what does the news mean for sun-seekers already in Portugal and what about people who have booked a holiday?
What should I do if I've booked a holiday to Portugal?
If you have an upcoming holiday to Portugal booked, the first port of call should be contacting your travel agent, tour operator or airline, Jennifer Morris, news editor at TTG, told ITV News.
Many travel companies have been offering more flexible booking policies recently due to the changing travel rules, for example allowing you to change your holiday up to 28 days before departure, so it’s definitely worth enquiring about your options.
What are my travel rights when countries are moved around on the traffic light system?
There is no automatic right to a refund when a country is moved from the green to amber list, Which? advises.
While the government advises against travel to amber destinations, most airlines and many tour operators continue to send holidaymakers to these countries.
What is crucial is the Foreign, Commonwealth and Development Office (FCDO) advice, which currently advises against non-essential to most, but not all amber countries and destinations.
An FCDO warning will trigger a refund for package holidays, but not flight only bookings.
If there is no FCDO warning, as with Portugal, you must rely on the flexible booking policy of your provider.
A handful of the best allow refunds for changing travel traffic lights, but most only allow rebooking - and this can cost more.
What if I'm already in Portugal - what do I need to do?
If you have booked a package holiday and want to come home early, contact your holiday provider to ask about your options, some may be willing to help change your dates.
Otherwise, you will have to pay for new flights if you want to get home before Tuesday and avoid the need to quarantine.
Based on travel corridors changing last year, this may prove costly as many people will be looking to return in the next few days - pushing flight prices up.
If I cancel my holiday to Portugal, am I entitled to a refund?
No, and it's not a good idea to cancel your holiday as this often forfeits your right to a refund.
There is no law prohibiting people from travelling to an amber list country for a holiday, although the government is urging people not to do so, this changes your rights when it comes to refunds.
Legally a holiday can still go ahead if a destination moves from the green to amber list, therefore there's no right to a refund if the holiday can still happen and is not cancelled by the provider, Jennifer says.
If you’ve booked a flight only and the flight is not cancelled, it’s unlikely you’ll get your money back simply because the destination’s traffic light status has changed.
If you’ve booked a package, you should be protected under the Package Travel Regulations, but only if the Foreign Office is actually advising against travel, which is separate to the Department for Transport’s traffic light system.
However, you may not be protected under the Package Travel Regulations simply because the traffic light status of the destination has changed
The best way to find out your rights is to contact your holiday provider, as they may be offering more flexible terms.
Some firms, including Exodus, Kuoni and easyJet Holidays, have been praised by consumer group Which? for their flexible policies.
Check the wording of your travel insurance policy to see what you're covered for.
5 tips to help avoid getting caught out if your holiday destination is put on the amber list
Check the FCDO advice - One of the biggest potential risks for UK travellers this summer is that they book a holiday to a green list destination which is later moved to the amber or red list. This alone won’t trigger a refund. But the separate FCDO advice can if you have booked a package holiday - the FCDO currently advises against travel to most, but not all amber list destinations.
Contact your tour operator or airline - If your destination is on the amber list but does not have a FCDO warning, like Portugal, airlines and most tour operators won’t offer you a refund. You will probably be able to postpone, although new dates can be more expensive.
If you need to get home quickly - If you are in a green destination which is joining the amber list and need to get home before the rules change, you should speak to your tour operator or airline about moving your flight forward. Most have flexible booking policies. However, prices may be high. Given the risks, it’s only sensible to travel this summer - even to green list destinations - if you are able to quarantine on your return to the UK.
Book a package holiday - Package holidays have greater legal protections if things go wrong - including refunds if the FCDO advises against travel, or if the company goes bust as a result of Atol protection. You won’t have these protections with an airline only booking.
Flexible booking policies - Anyone thinking about booking a trip anywhere in the next few months should book with a holiday company that has the most flexible booking policies available, including those that offer refunds if a country goes from green to amber.
What are the travel rules for countries on amber list?
People returning from Portugal and other amber list destinations must self-isolate at home for 10 days. They must take a pre-departure test, and PCR tests on day two and day eight of your arrival in the UK.
If you pay for a private Covid test through the Test to Release scheme, taken at least five days after arrival, you can end your quarantine early.
For travellers returning from green list countries, you do not need to quarantine, and for red list countries you must enter a quarantine hotel for 10 days and take a pre-departure test, and PCR tests on day two and day eight of your arrival in the UK.
Do the rules cover people in England or the whole of the UK?
The change in guidance for Portugal only applies to people living in England, but the rules have largely been mirrored by Northern Ireland, Scotland and Wales - so expect similar announcements from the devolved administrations.
Listen to our coronavirus podcast
Which countries are on the green list?
Now that Portugal has been removed from the green list, there are now just 11 countries remaining on the green list and most of the destinations are not viable tourist routes, as the majority are closed to international tourists, such as Australia, New Zealand and Singapore.
Israel and Jerusalem
South Georgia and South Sandwich Islands
St Helena, Ascension and Tristan da Cunha
Will the changes be enforced immediately?
It's unclear at the moment when Portugal will move from the green to amber list, but travellers may be given a few days to return home to avoid the quarantine requirements before they come into force.
Can I visit an amber country as long as I quarantine at home when I get back?
Although there is no law prohibiting people from travelling to an amber list country for a holiday, the government is urging people not to do so.
Can I book a trip to amber locations?
Some companies are selling and operating trips to amber countries, but UK travellers are urged not to book a trip to Portugal now it has been moved to the amber list.
Stay up to date with the changing travel situation in the UK and abroad with news, information and advice at itv.com/holidaynews.