Whoever it may be, they’ll have a fiendishly difficult act to follow.

It’s not often managers get to bow out on a high, but there can be no question Ange Postecoglou leaves Celtic in a considerably better place than the shell-shocked position he found them – disconsolate and surrounded by the rubble of ten in a row.

Five trophies from six, a world-record eighth treble and a guaranteed place in next season’s Champions League group stage; there is no hyperbole in positing that this gig has never been more appealing.

There is no man the Celtic fanbase would have preferred to take the club even further forward than Postecoglou, but the lure of Tottenham Hotspur and the Premier League would be far too strong for most managers to reject, never mind a 57-year-old who has been made to wait so long for the big jobs to present themselves. And so, Celtic’s hierarchy begin the process of locating the man capable of following him.

The successful candidate will pick up keys to what is unmistakably the house Ange built. This is a squad, and a club, now very much moulded in Postecoglou’s image, but that does not necessarily mean there is no one else who can make it a comfortable home.

As the search furrows on, a keyword in any and all discussions is surely ‘continuity’. The last time Celtic moved to appoint a manager, they did so in crisis mode. There was no discernible style of play, recruitment had been off-colour and the top players already in the building were lobbying to leave in the coming summer.

Few expected Postecoglou to transform matters as quickly as he did. But not only did he swiftly restore Celtic as Scotland’s dominant force, he laid crucial foundations for the future, ensuring his successor need not conduct a root and branch restructuring.

READ MORE: Ange Postecoglou explains Spurs move and opens on Celtic's bid to keep him

The ‘next cab out of the rank’ – as Postecoglou described his own appointment – need only prove they can continue this trajectory, not rip it up and start again. It’s why Bodo/Glimt’s Kjetil Knutsen looks such an interesting proposition.

The 54-year-old has been widely lauded for his work in transforming the Norwegian also-rans into league title winners and a credible proposition in Europe. Celtic fans need no reminder of the football Knutsen’s side played in wiping the floor with Postecoglou’s team in the Europa Conference League in early 2022.

At the time, it felt like watching an advanced version of what Postecoglou was in the process of striving for in Glasgow; a focus on wingers, full-backs heavily involved in build-up and a dynamic, technical midfield running over the top of their opponents. It is a philosophy that delivered one of the most eye-catching continental results of recent times – a 6-1 demolition of Jose Mourinho’s Roma, a side who have since won the Europa Conference League and reached the Europa League final in successive seasons.

But there’s more to Knutsen’s candidacy than simply replacing one attack-minded coach with another.

What has arguably been most striking about Postecoglou’s work with Celtic is the culture he has created. The Greek-Australian’s ‘we never stop’ mantra quickly permeated the Scottish football lexicon and, seemingly, burrowed its way the minds of everyone within Celtic.

‘Relentless’ is the word so often chosen to describe his team. Listening to his players speak at press conferences or after matches, it was blindingly obvious they had all been drilled in the same way of thinking, that the only game that mattered was the next one.

You could argue this was just effective PR training, but rarely will you hear so many different players, all with varying personalities, sound so uniform in their message and how it is conveyed. I’m not going to sit here and pretend I’ve listened in on any Bodo/Glimt pressers of late, but you do not build a club the way Knutsen has without having everyone pulling in the same direction with every ounce of energy in their body.

READ MORE: Celtic chief in 'unity and strength' vow after Ange Postecoglou's exit

That is what Postecoglou instilled at Celtic, and was no small contributor to the immense level of buy-in he soon received from supporters after what was an initial period of scepticism. Key to success for any manager is making sure you take the fans along for the ride, and that usually only happens when they can see the players are all-in, too.

I’ve spied a fair few supporters understandably vowing to revise their future levels of attachment to managers, but Celtic fans do love a strong figurehead, especially one with Postecoglou’s inimitable strength of character.

Knutsen is the face of Bodo/Glimt’s remarkable rise, he has a track record of success and instilling winning cultures that other contenders, such as the frequently mentioned Enzo Maresca, do not. He would not arrive with the baggage of a Brendan Rodgers, nor the stylistic suitability questions of a David Moyes. Whoever comes next must possess the tools to work with a squad which has been assembled for full throttle football.

If it is not already, Knutsen’s work in inspiring his team to punch significantly above their weight on the continent should be of serious interest to Celtic. What Postecoglou could have achieved in next season’s Champions League will forever be the great unknown of his Parkhead tenure – it was an obsession that convinced some he may even feel compelled to decline Spurs’ advances to see it through.

But he moves on with European performance as the one blot an otherwise near-flawless copy book. His rapid success in making Celtic Premiership champions again did not translate to continental competition in his first season, and his side were eliminated from all three UEFA tournaments. There were some seeds of optimism sown in last season’s Champions League but, ultimately, Celtic exited stage-left without a victory to their name.

Smashing the European glass-ceiling really ought to remain the club’s next great collective aim, even after Postecoglou has gone. As Celtic celebrate a fifth treble in seven seasons, for how much longer can trampling over the same domestic opponents and their comparitively miniscule resources really be the yardstick for success?

Yes, Celtic have not always maximised their many advantages over the majority of domestic opponents to the extent they currently are, and this conveyor belt of trebles is no mean feat. But Postecoglou fostered a real sense that the club can aspire for more in Europe while still respecting the bread and butter of SPFL business. He was right.

The anointing of a new manager should have that ambition as a primary consideration, and Knutsen certainly fits the bill. He has, however, been strongly linked with the Ajax job, so any approach may have to be a swift and highly convincing one.

But Celtic do have a strong case to present.

READ MORE: Celtic issue update on next manager search as club reveal 'priority'

Champions League football, a squad packed with young talent, ample funds to improve it and a unified fanbase ready to get behind the next man in charge. All the elements are in place to be sustained and built upon.

Tottenham hiring Postecoglou also further cements Celtic’s reputation as a gateway to the Premier League. And while that’s not the easiest pill to swallow for supporters ill at ease with their club’s position in modern football’s food chain, the reality is if they wish to continue courting ambitious coaches then they must reconcile with the fact that, if those coaches do their jobs, they likely won’t be in Glasgow long-term.

That is, unfortunately, the way of the world in 2023. But it does not mean Celtic cannot play it to their advantage.

They did so spectacularly with Postecoglou, they can do it again with Knutsen.