Passengers arriving at Heathrow Airport are finally having temperature checks for coronavirus – almost four months after the outbreak hit Britain.
But the thermal cameras screening, which began on Thursday, is being limited to a trial in an immigration hall at Terminal 2.
And the system monitors the temperature of multiple people moving through the airport, rather than testing individuals.
If successful, it could be rolled out to other areas, including departures, connections and staff sectors.
But Public Health England has consistently insisted checking temperature of passengers “holds little clinical value”.
The technology at Heathrow is similar to that used at many Asian airports.
Airport chief executive John Holland-Kaye called for a “common international standard” for health screening at airports to be agreed worldwide.
He said: “As one of the world’s great trading nations, the UK should take a lead in setting a global plan to reopen borders, when it is safe to do so.
“This will help protect millions of British jobs that rely on aviation, but are currently at risk.”
Gatwick Airport is also believed to be considering a trial of temperature checks alongside other measures, including social distancing, due to be announced in the coming weeks.
There has been anger over the lack of checks on air travellers arriving in the UK, especially from countries with high rates of Covid-19 infections.
Thousands of Atletico Madrid fans were allowed to travel to Liverpool for a Champions League game on March 11.
Health officials have looked at a potential link between the influx from the Spanish city, which was already under a partial lockdown, and a later spread of coronavirus in the Liverpool area.
Passengers arriving at Heathrow in January from the Chinese city of Wuhan – the seat of the outbreak – said they were not screened.
Several countries, including the US, Malaysia and Singapore, all required those travelling from Wuhan to have their temperature taken.
Before the crisis, 80 million passengers passed through Heathrow each year.
Numbers collapsed by 97% in April, with just 200,000 passengers in that month – the same number it would typically serve in a day.
A source said the new checks were as much about reassuring passengers who had temperature screening before they got on the plane abroad.
A number of other countries have been testing temperatures of travellers in a bid to limit the spread of the virus, which has so far killed 331,525 around the world.
They include Singapore, where just 23 people have died from Covid-19, and South Korea, which has had 264 deaths.
Airlines in North America and Asia have announced mandatory temperature screening.
Air France said it will now “progressively implement checks on all departures”.
It comes as the European Union Aviation Safety Agency this week published guidelines that could radically change the way people fly.
Travellers will have to wear face masks. Airport operators should set up interview booths for people with a high temperature to assess possible illness.
But the EASA warned temperature screening is not considered effective at spotting Covid-19 and is more intended to “dissuade ill people from travelling”.
Public Health England said: “PHE has offered to work with Heathrow to help design and evaluate a limited trial of temperature screening. This will help to inform the UK response.
“The UK has no temperature checks as they hold little clinical value as advised by the Government’s expert advisory committee, SAGE. Expert advice is that screening would detect a very small number of cases.”
The Department for Transport would not comment.
Home Office officials are expected to confirm details soon of a 14-day quarantine on arrivals to the UK.