The 16-year-old attacker plays for Belfast club Linfield, managed by former Whites hero David Healy, and has courted interest from top clubs in England and Scotland since bursting onto the scene last year.
Chelsea, Spurs, Liverpool, Manchester City and Glasgow Rangers are all among the clubs to have shown an interest in Allen, who made his senior bow aged 15 years, five months and five days, becoming the Blues’ youngest-ever debutant and capping the appearance with an assist.
He was included in Healy’s 25-man squad for a Champions League qualifier with Rosenborg and would have made competition history had he featured.
At Christmas in 2019 he starred and scored for Linfield Swifts in a Steel & Sons Cup final win over Newington, with a host of scouts in attendance.
Before the season was curtailed by the coronavirus pandemic, Allen had made seven first-team appearances, six of them as a substitute.
Sources in Belfast suggest Leeds are leading the race to sign the youngster, who can play in midfield or as a forward and the Whites feel they are in with a good chance, having tracked him for a long time.
But a deal is not thought to be imminent, with Leeds United’s playing staff, coaching staff and senior management having taken a pay deferral to safeguard the jobs of hundreds of clubs employees, and transfer movement on the backburner.
Linfield’s academy director Glenn Ferguson last month expressed his preference for Allen to make a move to Leeds or another club outside the top flight, over one of the Premier League giants.
“Charlie over the course of the year has been to Liverpool, Manchester United, Manchester City, Tottenham and Chelsea were interested,” he told The Belfast Telegraph.
“With all due respect, Manchester City can go and get 20 Charlie Allens from across the world.
“He’s maybe better off going to a club like Ipswich or Leeds where someone like Stuart Dallas can take him under his wing.
“If he joins a Championship club like Stuart Dallas and Gavin Whyte did, he can progress from there. They need to be playing football when they do go there.
“The big clubs sound good but only one in 30 of the young players Manchester City might sign will eventually play in the first team.”
Former Ipswich and Northern Ireland midfielder Jim Magilton is the elite performance director for the Irish Football Association, helping to prepare young players for the professional game.
He rates Allen very highly, as a youngster with a “real chance” to make it.
“Charlie is one of those boys that you throw him on to the park and go and ask him to play,” he told The YEP.
“[He’ll] play anywhere with the same attitude and enthusiasm.
“Technically very good and physically can handle it – he is quick enough and he has a real chance.
“Great attitude, enthusiastic, and applies himself every day.
“He’s been in full-time academy from September and he’s been excellent.”
Patrick Van Dort, deputy sports editor for JPIMedia in Northern Ireland, has been impressed by what he's seen and heard of Allen since his breakthrough.
"I've watched him a few times, coming on for Linfield and in terms of the buzz around him, people seem to be impressed with his ability to adjust to that next level, that next challenge and the maturity he has," said Van Dort.
"He doesn't try to do too much, he doesn't get flustered on the ball, speaking to team-mates they trust him.
"Fans have compared him to Billy Gilmour [Chelsea teenager] in terms of playing style, he's got game intelligence and at first team level for Linfield he's been disciplined.
"People say he's a dream to coach, a good listener and ticks the boxes you'd expect of someone so highly rated."