England boss Gareth Southgate was last night left scratching his head as to why two of his stars have been forced into isolation after hugging Covid-positive Scotland midfield Billy Gilmour - while players with whom he shared a dressing room will be allowed to play-on.

The puzzled Three Lions boss raised the question last night after it was announced that Ben Chilwell and Mason Mount would be forced to quarantine following Gilmour's positive test result.

It comes after the trio, who all play for Chelsea, were pictured hugging at the end of England and Scotland's 0-0 Euro 2020 draw at Wembley on Friday night.

Gilmour later tested positive for Covid and is now isolating. Chilwell and Mount will also have to quarantine, despite twice providing negative Covid test results since.

To add to the confusion, Scotland's manager Steve Clarke and several teammates, who were also pictured in close contact with Gilmour during Friday night's clash, will be allowed to continue as usual ahead of their game final group game against Croatia tomorrow.

It is a decision which raised the eye-brow of Southgate, who said last night: 'I don't want to cause a drama for Scotland, but if you're all in the dressing together room. Where do you stand?

'I don't know all of the factors behind that but it clearly it's nothing to do with being on the pitch.'

Southgate, meanwhile, said he would remind players not to hug their club teammates during the tournament, in the hope of avoiding a similar situation in the future.

It comes as confusion remain over who told Mount and Chilwell to self-isolate. Public Health England claim they had not advised the FA or SFA to advise them to self-isolate.

The move to quarantine Chilwell and Mount could prevent them from participating in tomorrow's final group game versus Czech Republic. They could also be forced to miss the start of the knockout stages which start next week.

Some fans had earlier been left 'baffled' that England stars would not be regarded as 'close contacts' of Gilmour, despite playing on the same football pitch for 90 minutes.

But others have questioned why only Mount and Chilwell have been told to quarantine and Scotland players have so far not.

Manager Steve Clarke was seen talking face-to-face with Gilmour after the midfielder was substituted off during the game, while striker Lyndon Dykes was also seen hugging the young star at full-time.

A video, posted and later deleted by Liverpool and Scotland left-back Andy Robertson, also showed him and Gilmour playing table tennis with teammates back at Scotland's Euro 2020 base.

Football presenter Gary Lineker was one to raise concerns, saying it was 'odd' that Mount and Chilwell would be forced to self-isolate even though they had already tested negative for Covid.

He said on Twitter: 'This is odd. They may have had close contact with Billy Gilmour, but If they continue to test negative surely they can play.

'Otherwise surely every single Scottish player, who all hugged Gilmour after the game, won't be allowed to play either. Makes no sense. '

Another, footballer presenter Olivia Buzaglo, added: 'Mason Mount and Ben Chilwell isolating after coming into contact with Billy Gilmour...

'What about all the Scotland team that would've been hugging him after the game? Andy Robertson playing table tennis with him? I'm confused a little.'

It comes as it emerged that England's footballers won't receive extra coronavirus tests despite Gilmour testing positive for Covid-19 just three days after facing them at the Euro 2020 championships.

According to NHS England, in normal situations, close contact means 'close face to face contact (under one metre) for any length of time – including talking to them or coughing on them.

It also includes being within one to two metres of each other for more than 15 minutes – including travelling in a small vehicle.

In normal situations, NHS Track and Trace will alert a person if they have been in 'close contact' with someone who has tested positive for Covid.

In those circumstances, a person will be told to stay at home for a full 10 days following the contact.

Anyone you live with will also need to self-isolate at the same time.

You should also self-isolate if you have Covid symptoms, such as a high temperature, a new, continuous cough or a loss or change to your sense of smell or taste, if you or anyone you live with test positive for Covid, or if someone in your support bubble tests positive and you have been in close contact.

The 20-year-old Chelsea footballer will now be forced to self-isolate for ten days, hours after playing a major role in Scotland's goalless draw with England at Wembley Stadium last Friday in his first start for the national team.

All 26 England players and the support team returned negative results after the latest round of PCR testing by Uefa yesterday - and the full squad trained at Spurs Lodge in Chigwell today.

But they have received no further tests because they were not deemed 'close contacts', despite being in close proximity to Scotland's stars at the match.

No other Scotland players have been affected or identified as close contacts, meaning all will be available as they face Croatia in a winner-takes-all Group D clash at Hampden Park in Glasgow, which is also tomorrow at 8pm.

All Scotland's other 25 players tested negative for Covid-19 after lateral flow tests following training today, but the lack of players being defined as 'close contacts' or extra testing for England provoked outrage on Twitter today.

Twitter user Stuart Graham said: 'So I'm really confused, if a pupil in my daughters class 'bubble' tests positive for Covid then the whole class will isolate, yet Billy Gilmour tests positive yet Scottish team don't have to self-isolate.'

Another tweeted: 'I'm honestly baffled with this Covid-19 nonsense, how can they say no one is considered as a close contact to Billy Gilmour when all the players shared the same dressing room etc - totally f***ed up.'

And a third added: 'So Billy Gilmour has to isolate but the entire team, whom he has been in very close contact with, don't. Yeah, right, that makes perfect sense. If a kid in class tests positive the whole class are sent home. Get an effin grip. It's all utter nonsense.'

The Scottish and English football associations remained in talks with Public Health England this morning regarding close contacts of Gilmour, but none have been identified.

It's difficult to know exactly when the Scottish starlet contracted Covid.

It generally takes four to five days for the virus to 'incubate' in someone before they start shedding enough to test positive.

This would suggest Gilmour, who produced a positive result on Sunday, picked up the virus sometime last week.

The midfielder would have tested negative last Wednesday, two days ahead of Scotland's clash with England, because UEFA rules mean all players, coaches and supporting staff need to take a swab 48 hours before each match.

It's possible that Gilmour was technically infected with the virus at that point and that it had not yet multiplied in his system enough to show up on the test.

If this was the case, then it is also possible that the Chelsea star was infectious by the time he took to the pitch at Wembley on Friday evening.

While UEFA requires a negative test two days before each match, players are only checked for their temperature on matchday.

Many infected people go undetected by temperature checks because only a handful of Covid patients suffer a fever. Fit and healthily 20-year-olds like Gilmour are much more likely to be symptomless while infected.

There is a slim chance that Gilmour's positive result on Sunday was a 'false positive', when the test wrongly tells a person they are infectious.

While the PCR method is highly accurate, some studies have shown they can give a false positive up to 4 per cent of the time.

UEFA's stringent testing protocols stipulate that players cannot challenge a positive PCR test or ask for it to be redone.

However, assuming that Gilmour was infected at the time of the England game, it raises concerns that others could also have contracted the virus.

Gilmour was seen hugging some of his Chelsea teammates after the match -and there could now be doubts over both Ben Chilwell and Mason Mount prior to England's final group game against the Czech Republic tomorrow.

He was also seen embracing his Scotland teammates and manager Steve Clarke on the pitch.

Covid finds it easier to spread when people come into close contact with others, which is why we were urged not to hug loved ones and friends for months during lockdown.

But being outdoors in the fresh air significantly reduces the likelihood of the virus being able to jump from person to person.

However, Gilmour was also recorded celebrating with teammates in the changing rooms and interacting with his parents in the stands on Friday night.

Footage then surfaced of the Glaswegian playing table tennis in close proximity with members of the Scotland squad at the team hotel over the weekend.

UEFA has stressed that all 26 England players and the support team, as well the rest of the Scotland squad, returned negative results after the latest round of PCR testing yesterday.

But the virus' incubation period means there is still a risk some of them may have caught the disease.

An SFA spokesman said: 'The Scottish FA can confirm that a member of the Scotland national team playing squad, Billy Gilmour, has tested positive for Covid-19.

'Having liaised with Public Health England since the positive test was recorded, Billy will now self-isolate for 10 days and therefore miss tomorrow's Uefa Euro 2020 Group D match against Croatia at Hampden.'

Gilmour will play no part in tomorrow's match for Scotland, who are in their first major tournament since World Cup 1998. They sit bottom of Group D with one point and need to beat Croatia to have a chance of progression.

Scotland have not yet confirmed if Gilmour has received his Covid-19 jabs, but this is viewed as unlikely due to his young age and involvement in elite sport which would mean he may not want to risk getting any side effects.

Half a dozen other teams in the tournament, which has been delayed by a year, have also suffered Covid-19 cases - and Gilmour's positive test is the second to hit the Scotland camp since the squad met up earlier this month.

All Euro 2020 teams are living in a bubble and avoiding all contact with the public for the duration of their involvement in the tournament. Players are having regular PCR tests - with everyone getting tested 48 hours before every match as per UEFA regulations - and their temperatures are taken when they arrive at stadiums.

Any player, coach or official who returns a positive result is immediately removed from the group and quarantined, followed by universal testing of the entire squad and any known contacts.

Opposition players are not deemed close contacts unless they spend an extended period of time with the positive player.

Guidance from England's FA states match play is not considered 'close contact' so no action is needed unless individuals experience symptoms, in which case they must self-isolate from that point as per Government guidance.

Sheffield United midfielder John Fleck sat out both of the Scots' warm-up fixtures against Holland and Luxembourg after contracting the virus, and another six players missed the 2-2 draw with the Dutch as a precaution, although they were not formally designated close contacts of Fleck.

Soon after news broke of Gilmour's positive test at about 10.30am this morning, a video surfaced from the team hotel where the young midfielder was seen enjoying playing ping pong.

Taken on Andy Robertson's Instagram story, the video shows Gilmour, along with John McGinn, unwinding with a game in the team hotel. The video has since been deleted from the Liverpool full-back's Instagram account.

Sportsmail has learned that there are no close contacts in the Scotland camp that will be forced into isolation as a result of the positive test.

Gilmour was left out of the side for the opening group defeat to Czech Republic but proved a revelation in the match at Wembley against England.

Both Scotland and England players are routinely tested for Covid-19 and the task now will be to determine if Gilmour is merely an isolated case of a positive result.

The Blues youngster was hailed by Patrick Vieira, Graeme Souness and Gary Neville as a difference maker in 76 minutes at Wembley in what was his first start for his country.

'I really love his technical ability. He loves to get on the ball,' Vieira said on ITV. 'His team-mates aren't scared to give him the ball because they know how good he is on the ball. I think he has a really good future ahead of him.'

The youngster has been so impactful in the early part of his career that he has claimed the man-of-the-match gong on his first appearances in the Premier League, the FA Cup, the Champions League and the Euros.

Gilmour was almost certain to be the leader of the midfield on Tuesday at Hampden for the match-up against Croatia. But his enforced absence arrives as a crushing blow for Scotland and their hopes of progressing.

Even if Scotland progress without him, his 10-day isolation period would also rule him out of any last-16 tie all but ending his Euros run after one game.

Having outshone a string of Premier League players on Friday night, Gilmour was expected to start again against Croatia, with the tantalising prospect of him going head-to-head with Real Madrid midfielder Luka Modric.

But manager Steve Clarke will now need to rethink his plans. Manchester United midfielder Scott McTominay, who slotted back into a defensive role against England, is likely to be returned to his usual position protecting the back three. Clarke is due to hold a press conference today at 5.45pm.

Earlier this year, experts told the Sunday Times in March that there had not been a single instance of on-field transmission of Covid-19 in UK football, rugby union, rugby league or American football.

Professor James Calder, the independent chairman of the government's committee on the return of elite sport, said all instances of Covid-19 being transmitted within football had happened away from the pitch.

He said at the time: 'We have not had any cases of transmission on the pitch in football. It is what happens off the pitch, in the changing rooms, car-sharing, [not] social distancing that appears to be the risk.

'There was concern contact sports such as rugby could have very different problems compared to football and cricket but those sports have done very good work to identify the risks on the field.'

A Premier League study last year showed players would be within the infection distance of two metres, if one player on the pitch had the virus, for an average of just 39 seconds during a match.

All football teams competing in Euro 2020 are living in separate bubbles and having to avoid all contact with the public for the duration of their involvement.

Players are having regular PCR tests for Covid-19, including one done 48 hours before a match, and their temperatures are taken when they arrive at stadiums on the day of a game.

Any player, coach or official who returns a positive Covid-19 result is immediately removed from the group and quarantined in order to contain any potential outbreak. Team-mates or staff who have had close contact with the infected players must do the same.

Opposition players are not deemed close contacts unless they spend an extended period of time with the positive player. Teams must fulfill their Euro fixtures as long as they have a minimum of 13 players available.

The FA ran Covid-secure bubbles throughout England's UEFA Nations League matches and World Cup qualifiers over the last year without any players being infected, but the length of Euro 2020 has placed different demands on those involved.

Last month it emerged that the families of England players would be banned from visiting the team hotel during the Euros due to the Covid protocols.

Manager Gareth Southgate said at the time: 'We're not going to be able to let people in. There's a clear edict from UEFA on what the bubbles need to look like to be as secure as we can make them. It's never going to be 100 per cent failsafe but we've got to comply with as much as we can.'

England's players have been in their bubble since June 8, having been allowed the previous day off to go home to see their families before the tournament began.

Teams had to enter their respective bubbles five days before their opening match and must remain there until the completion of their final game in the competition.

England played Croatia in their first game at Wembley on June 13, and could be in the bubble until July 11 - the day of the Euro 2020 final.

Southgate had allowed players to meet up with loved ones during the 2018 World Cup in Russia, which stars used for day trips into St Petersburg.

Headlines during England's 'Golden Era' were often dominated by the antics of partners of the playing squad - termed as 'WAGs' (Wives and Gilrlfriends).

After the 2006 World Cup, Rio Ferdinand said coverage of WAGs was 'like a circus' and 'football became a secondary element' as England were eliminated at the quarter final stage.

Former England boss Fabio Capello infamously banned his players from contact with their other halves during the 2010 World Cup, much to the ire of his players.