Love them, or loathe them, British tourists are back in Greece and Athens’ tourism minister has wasted no time in expressing his delight.

Greeks were “very, very happy” that Britons were finally returning, Harry Theoharis said. “We always enjoy the company of our friends from the UK,” he told Sky News as air links resumed on Wednesday. They had been suspended since March, although that didn’t stop Boris Johnson’s father, Stanley, travelling to his Aegean villa despite British nationals also having been advised to avoid all but essential international travel.

And it appears the feeling is reciprocated: within 24 hours of the flight ban being lifted, around 1,200 Britons had landed in Greece. And by Friday, a reported 200 planes had flown from the UK to the country’s 18 regional airports.

On Zakynthos and other Ionian isles that rely almost exclusively on British tourism, the relief is almost palpable. At this time of year tales of drunken debauchery and misbehaving Britons have usually eclipsed the local news and exhausted those who must handle the fallout in the travel industry.

“Today, we can’t wait to have them,” said Charalambos Varvarigos, the vice-mayor of Laganas, the Zakynthian resort often associated with youthful hedonism. “We have always had a big soft spot for the English even if some of them do drink. Only 60% of our hotels are open but they are beginning to come,” he said.

Britons are Greece’s most lucrative European market, with more than 3.5 million visiting last year. Their absence would cost €2.56bn for an industry that, at close to 25% of GDP, is the nation’s biggest.

With one in five Greeks reliant on tourism-related work, the sight of Britons signals a return to normality. But their arrival is also being treated with trepidation.

The spectre of people arriving from a country with “so many cases and so many deaths”, in the words of Greek health officials, has stoked fears of “imported incidents” and unease on islands that had so far remained remarkably coronavirus-free. As a result, UK holidaymakers are having to undergo mass testing in airport lounges nationwide.

Local media reports suggest up to 6,000 visitors from the UK will be tested this week, with soldiers being deployed to specially assembled health units on islands to administer swabs.

“The result of the mass testing … will determine if Greek borders remain open or not to Britain,” the leading Greek daily, Protothema, wrote. “If the number and percentage of those found to be positive is low, and is limited to under 30 to 40 cases, then with constant inspections and epidemiological oversight, the British tourist market will remain open.”

If not, the centre-right government would not hesitate to shut the borders again “calculating that the cost of the risk of the coronavirus spreading is much more important than any benefits to tourism in a year that is considered largely lost”.

There has been a significant rise in infections since Greece reopened its borders on 1 July – there have been more than 500 cases, and hospital admissions have risen from 41 to 83 in less than two weeks.

In a country that has recorded fewer than 4,000 cases and 193 deaths to date, epidemiologists are expressing their concern.

“If there are a lot who test positive from Britain I would not rule out scientists proposing that the borders close again to people [coming in] from the UK,” said Dr Andreas Mentis, the head of the Hellenic Pasteur Institute who sits on the expert committee that advises the government. “Too high a percentage would endanger the Greek population, and tourism more generally and we couldn’t accept that.”