The Magpies linchpin has departed Victory Park after being signed by the National League outfit for an undisclosed fee.
Signed in the summer of 2020 from Grimsby Town, Cardwell has scored 11 goals in 35 appearances for Chorley, including seven strikes from 14 games this season.
There had been plenty of interest in the burly target man but despite being linked with clubs in the Football League, the 25-year-old has opted to join the Shrimpers.
Despite currently languishing in 18th spot in the National League, Southend are certainly a big name who have spent the vast majority of their existence in the Football League, including a spell in the Championship during the 1990s.
While disappointed to lose Cardwell at such a crucial stage of the season with his men preparing to travel to National League North rivals Brackley Town in a crunch promotion clash this weekend, Vermiglio had been braced for interest in his talisman during the January transfer window.
And he admitted he could not stand in the way of the frontman's ambition to become a full-time professional player again.
"You know what, we took a little bit of a gamble on Harry a couple of years ago," said Vermiglio.
"It was a gamble in terms of he had a long-term injury which he was just coming back from.
"Most clubs probably would not have taken that risk but we invested a lot of time in securing the deal.
"We then invested a lot of time and effort with him physio-wise, recovery-wise, to get him back to the player that we thought he could be.
"I am pleased that he was able to do that with us over time.
"I think he's gone from strength-to-strength as a player and playing at this level has done him a world of good.
"He's played his most consistent football, his most regular football and he's scored some really important, crucial goals for us.
"In the main, his performances have been outstanding and he has become more consistent and a tougher player to come up against.
"It's been no surprise that there's been a lot of interest in him and no surprise from the player also. He wanted to leave and go back to full-time football.
"We always agreed that if a good opportunity came up which was good for the club and, in particular, good for him, then we would explore it.
"We have done that and he's managed to secure a move.
"We reluctantly have allowed him to leave. I want to make it clear, I wanted to keep him and I wanted to keep the lads together.
"But at the end of the day when you have a player who wants to go and play full-time football, it's very difficult to stop that - we couldn't stand in the way.
"He's ambitious to play in the league above and the league above that.
"He goes with our best wishes. We don't want to stand in the way of him and that's always been the message to our players.
"If there is something which is right, then it is a proud moment in some respects, knowing that you have helped a player develop and kick-on in their career."
Despite speculation over his future in recent weeks, Cardwell's head was not turned by the reported interest and he remained completely committed to the Magpies.
"I would say there's been interest in him from five or six clubs from the league above and League Two," said Vermiglio.
"The last couple of months have been tricky for us because we've known there has been interest in him but Harry has been thoroughly professional in terms of his performances.
"I have always been transparent with the interest in him. I always said I would do that.
"But he's always been 100% committed to our cause and I think we have seen that in the last six or seven games where he's had all this going on but he's been very professional."
Born in Yorkshire, Cardwell began his career at Hull City as a junior before joining Reading as a youth team player.
He failed to make a single appearance in the first-team with the Royals and spent time on loan at Woking and Braintree.
He also spent a period with Brighton and Hove Albion's Under-23s, but his career finally had lift-off when he moved to Grimsby Town.
A three-year stint with the Mariners followed before he eventually signed for Chorley.
In his 18-months at Victory Park. Cardwell has become a key figure despite the difficulties of the Covid-19 pandemic.
Last season, he was immense as Chorley remarkably reached the fourth round proper of the FA Cup.
He scored in the first round proper as the Magpies came from behind to beat League One Wigan Athletic 3-2 at the DW Stadium and was the man-of-the-match as Chorley defeated Peterborough United 2-1 at London Road in the next round.
A Covid-19 depleted Derby County were brushed aside in the third round 2-0 at Victory Park and Cardwell then went on to serve notice of his abilities by giving the defence of Premier League Wolves - which included England international Conor Coady - a torrid time in the fourth round .
The Wanderers eventually prevailed 1-0 in a tight game.
When the 2020-21 National League North season was curtailed due to the pandemic, Cardwell moved on loan to Stockport County for the rest of the season.
It is believed the Hatters were keen to take him permanently and were close to securing his signature this season, but the deal fell through.
Vermiglio believes Cardwell has got the ability to be a success in the National League and beyond that.
"I am confident that he can do well at the next level," Vermiglio said. "Without doubt he can kick on and hopefully he can go from strength to strength.
"He's been phenomenal for us and perhaps has not scored the goals that he's deserved for his performances.
"He's hit the post on numerous occasions and shot just wide on numerous occasions or the goalkeepers have made some great saves.
"He is inches from being a 20-goals-a-season man
"I am hopeful that will come for him but in terms of an all-round striker, a No.9, his performances have been terrific.
"To to be able to hold it up and win flick-ons like he does, to be good in both boxes like he is, he can run in behind, he is big and strong.
"The good thing about Harry is he's a good listener too."
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