Joe Hart's arrival at Celtic was far from straightforward.

From the player's perspective – then aged 34 and on the furthest fringes of Nuno Espirito Santo's newly-inherited Tottenham squad – game time came at a premium.

By the player's own admission, had the chance to travel north not materialised when it did (for an astonishing £1 million fee, no less), retirement from the game altogether was not beyond the realms of possibility for the experienced one-time England international goalkeeper.

Which seems ridiculous now. This is the man who was immortalised by Roberto Mancini's Manchester City title-winning side. The man who, after Sergio Aguero scored that last-gasp goal against Queens Park Rangers in the final seconds of the final day in 2011, was seen sprinting in circles on the Etihad grass, arms aloft and mouth agape, consumed by the euphoria that underpinned one of English football's, perhaps even world football's, most exhilarating afternoons.

From the club's perspective, so much rested on Hart's shoulders. After a hugely disappointing season the year before, that saw Celtic finish 25 points behind rivals Rangers, change was in the air. Vasilis Barkas, Scott Bain and Connor Hazard had shared the number one spot over the course of the 2020/21 trail, but none had made the jersey their own.

New manager Ange Postecoglou, a relative unknown before moving to Scotland, was yet to prove himself, and, still in the throes of the pandemic's harsher restrictions, Hart signed for Celtic at a time of global uncertainty.

It was reality TV show Love Island, of all things, that I first observed Hart and newly-named club captain Callum McGregor share a bond over.

Working for the club's media team at the time, I conducted Hart's first-ever Celtic interview – me in my house in Glasgow, and Hart in a hotel room in the Czech Republic; the goalkeeper having flown straight to his teammates ahead of their Europa League third qualifying round encounter with FK Jablonec after putting pen to paper.

During the interview itself - held remotely on Zoom, 1,200 miles apart - Hart spoke enthusiastically about the challenges ahead and his unwavering desire to leave his mark on Celtic and Scottish football.

As the 37-year-old now stares down the final game of his career this weekend in a Scottish Cup final against Rangers, I don't think anyone would disagree that he has succeeded.

Off camera, however, I observed an instant chemistry between McGregor and Hart as they joked about the guilty pleasure of enjoying ITV's popular reality dating show, and it was immediately clear that if anything underlined the transitionary period Celtic were forced to endure, and ensure, at the time, it was this exchange – two players: one a veteran of the game, the other a stalwart of the club.

Needless to say, that relationship grew and has continued to grow on the pitch ever since. The pair have lifted the same six trophies in three years while sharing a team sheet, and the scenes and comments the two have shared in the last 10 days, since Celtic secured a third consecutive league title, have warmed the hearts of fans the world over.

Hart has nothing but praise for the Celtic captain, and vice versa, which makes listening back to what the former said about the latter upon first impression almost three years ago seem even more powerful.

"Callum's been great," he said. "It doesn't matter how many times you've been in this situation or how many teams you've gone into, it's always quite daunting meeting new teammates.

"Callum was a class act, to be honest, made me feel at ease straight away. He's obviously been here, he's worked really hard with the previous captain, he's taken over and I can see he's got the respect of the lads.

"He's certainly got my respect and I look forward to working with him."

With that, Hart admitted he'd been in the captain and his new colleagues' company at the time of the interview for around 15 minutes, describing the experience as a whirlwind. Looking back now over the last three years of his career at Celtic, and those first steps through the door will, I'm sure, seem like nothing in comparison.

As for what Hart promised to bring to the club, he said: "I want to bring everything that the footballing world has thrown at me in the last… I feel old saying this, 17 years. I've seen a lot, been through a lot, lots of good, lots of bad, and the one main thing I want to bring is passion.

"I love football. I'd play football whether it be with my friends, my son at home, and I'm just so lucky that I've been able to play it at some serious stages, and hopefully I'm getting to do that at a huge club like Celtic.

"There's going to be passion, there's going to be energy, and hard work.

"Celtic is known all around the world, for those passionate reasons. Great fan base, great stadium, history, European nights, these are all the things that I'm really hoping to be a part of."

Whether or not Hart can finish his career with another winners medal with Brendan Rodgers and his current colleagues this weekend remains to be seen, but one thing is certain: that same passion Hart speaks of will be reciprocated around the national stadium on Saturday.

And it's in those moments, evidently, where Hart shines.