Scotland youth international Liam Miller is a prime example. The 19-year-old has 15 international caps but has been without a club since Sunderland released their under-18s squad en masse around the start of the first lockdown.

Miller has been training with the under-19 squad of Northern Premier League side South Shields and working four times a week with a performance coach set up through his agent.

"After the first lockdown, even if you managed to get a trial, it was difficult when you had been off for three or four months," Miller told the PA news agency.

"I was in at Forest and Brentford but they were looking for someone older, someone who can break into the first team right away."

Miller's agent, Dave Gordon, is concerned that teenagers who found themselves without clubs because of the extraordinary circumstances do not get left behind.

"A lot of these lads were getting released because of Covid," said Gordon, group CEO at Deluxe Sports Group.

"What was really frustrating was that some clubs were saying, ordinarily we wouldn't need to look at him, we would offer him a contract, but we haven't got the money to invest, we don't know if we can sign new players. Clubs at the lower end of the pyramid were furloughing players. A lot of scouts and heads of recruitment have been furloughed.

"We can't even set up trials for a lot of these lads because of Covid rules. Hotels are closed too.

"Clubs have had to do what they have had to do. It's been a really testing time for everybody, but we seem to be through the worst of it and hopefully these lads are ready to go now. The testing we have done with them shows that but even now trying to get players on trial is tricky.

"Some of the lads went out to play men's football, that could have been Northern League, National League North and South, and their seasons were curtailed.

"We had a goalkeeper who left Middlesbrough and has been training with York this season and he has been called in by a Championship club. So hopefully we are seeing this cycle come to an end, with Covid tests helping.

"Some lads will have got lucky but some lads will have slipped through the net.

"I hope that the lads who were out of contract last summer and have been grafting don't get forgotten about, that we make sure we work hard for them. I would say there are hundreds of them."

Gordon's firm restructured its business to help the young players.

"We had to bring in a full-time head of performance who is setting them nutritional plans and training plans and, when it's safe and Covid-compliant, been doing sessions, whether it's outdoors or on Zoom, and doing testing," he added. "Fortunately, these are young fit lads.

"One of our agents has come from a teaching background and has re-jigged half of his duties so he is head of education and welfare. One of the main things he is doing is warming them up for life after football and usually that doesn't really happen until they are 32 or 33. These are 18 and 19-year-old lads.

"We have a mental-health nurse the lads can reach out to and we make sure we keep in regular contact. The best thing we can do is support them in every way we can.

"These young lads have had everything taken away from them and we have to help them build everything back up."