The decision has only been made on 18 occasions in more than 150 years. Today, it is arguably more difficult, more stressful and more pressurised than it has ever been.

To appoint a Rangers manager is an honour and a privilege for a chairman or director, yet they do so in the knowledge that great power comes with great responsibility. 

John Bennett and James Bisgrove will know the feeling all too well right now. Just months into their tenures as chairman and chief executive respectively, the recommendation they are about to make will go on to, perhaps, define their reigns and shape their legacies.

It is a business decision, yet one that is made with the heart as well as the head. Those stress levels are natural given that tens of thousands have an opinion and emotional and financial interests, but the key calls are made by only a handful.

In any industry, you have to accept that a certain percentage of your customer base are going to have complaints from time to time. At Rangers, the stakes are higher and the repercussions are more severe, and that is just for the 50,000 that attend every few days. You can please some of the people some of the time, but never all of the people all of the time.

What is it like to appoint a manager at Ibrox? What are the key considerations, requirements and conversations required? The Rangers Review spoke with those who've made the call to find out...

“It is 1000 times more stressful than anything else you do."

The description made by one former Ibrox board member to the Rangers Review doesn't pull any punches.

"It is a huge pressure. There is no question that the most important person at the club is the manager. No question.

“In football, it is all based on the result of the match. If it is a bad result, half of your customers will complain about something. That is huge. That would be unmanageable in any other business. It is indescribable. The pressure is just crazy."

In a world of rolling news and social media, the intensity has never been as great on managers. Friends and family can so often provide a respite from a game and a position that can become all-consuming but they, like the wider community, can act with the benefit of perfect hindsight. The decision to, for example, name Michael Beale as boss was somewhat easier to justify last November than it was last week.

That burden can become too much. The pride and privilege of wearing the tie and serving the club can be outweighed by the knowledge that your judgements – no matter how well-intentioned or well-deliberated – will never meet with universal approval, even in the best of times. That is certainly not the case right now and no ruling will resonate as much as the hiring of a manager.

Rangers have been in this situation too often in recent seasons. The 19th permanent manager will be the fourth to hold office in two years and the departure of Steven Gerrard has acted as a catalyst for another period of instability at Ibrox. Before Gerrard’s arrival, Graeme Murty, Pedro Caixinha, Mark Warburton and Stuart McCall had all had stints as manager in their own right since regime change, while Murty, Kenny McDowall and Jimmy Nicholl had – like current interim gaffer Steven Davis – filled in out of a sense of duty during times of tumult.

READ MORE: New Rangers manager: Key calls as Bennett and Bisgrove step up search

Each of those permanent appointments were made with the right intentions. Some seemed like a good fit, others were somewhat of a risk. In the case of Caixinha, it was just pure madness.

Rangers are back in a cycle that must be broken. It was acknowledged even before the sacking of Beale earlier this month that the process of hiring and firing managers every season was not sustainable from either football or financial perspectives and the days since have been spent seeking to make an appointment that carries as little risk factor as possible.

That process has been overseen by Bennett and Bisgrove. When Frank Lampard was interviewed last week, Rangers also called on the advice of Graeme Souness. Ultimately, the talks progressed no further and the Rangers Review revealed on Friday that Lampard was out of the running.

Using club legends as conduits makes perfect sense. When McCall was tasked with trying to earn promotion from the Championship in 2015, the initial approach came from nine-in-a-row team-mate Richard Gough as one Ibrox legend sounded out another at a time when Rangers were in desperate need of someone who knew the standards and had the club at heart.

John Brown had also put McCall's name forward, as had Walter Smith. It was Smith who was first on the phone to McCall once he arrived at Auchenhowie, jokingly asking if he knew what he had let himself in for while offering the kind of advice that the next incumbent could only dream of receiving.

The identity of that boss has still to be confirmed and many names have been talked up and shot down during a process where the thirst for information has never receded but those at the heart of it have kept their cards close to their chests. From an initial batch of several dozen CVs that were compiled to begin with, Rangers were able to quickly whittle their candidates down as Bisgrove took the lead on the most significant task of his time at Ibrox.

By Tuesday afternoon, it had become clear that Philippe Clement and Kevin Muscat were the two horses left in the race. Rangers must now hope that they have put their money on the right man and backed a winner. The likes of Scott Parker and Pascal Jansen, the AZ Alkmaar manager, were also touted as potential candidates, while former Eintracht Frankfurt boss Oliver Glasner was overlooked despite making it clear he would be interested in a move to Scotland.

The ramifications of getting this one wrong are huge for Rangers and those that will ratify this decision – including directors and investors from across the globe – will need no reminding of that. Another Premiership title may already be beyond their reach and Celtic now have their sights on the same target of 55 that Gerrard was able to deliver. Seeing their Old Firm rivals reach 56 before them and overtake their trophy haul – and thus assume the mantle of the most successful club in the world – would be a bitter pill to swallow for Bennett, his board and his investors. Avoiding that scenario has been at the forefront of minds since the summer but the time, money and effort put into Beale has not been repaid and the high hopes that were shared and the targets that were set less than 12 months ago have not been matched or met.

At that stage, Bennett was still deputy to Douglas Park and Bisgrove was head of the commercial department rather than the man running Rangers on a daily basis. They shared a vision with Beale throughout the summer, but he had to be dispensed with before they became too guilty by association. A clean break now offers fresh opportunities and that will not have been lost during their discussions and deliberations in London over the last few days.

This one must, quite simply, be the right one for Rangers. The manager is and must always be the dominant voice and the leader in all regards, he is the most important person at the football club and the pressure on ensuring he is the right man for the role weighs heavily on his shoulders.

The two previous appointments were overseen by Ross Wilson and involved a delegation of executive and PLC directors. In both situations, the views of the supporters matched the interview panel and Beale and Giovanni van Bronckhorst were largely heralded and popular choices when they returned to Ibrox.

Before that, the move to land Gerrard had been driven by Dave King. A chance meeting at the top of the Marble Staircase sparked a lightbulb inside King’s head and he would later offer Gerrard the opportunity to begin his managerial career at a club where the demands and expectations ensured he would feel at home away from home.

“Steven is a very interesting story in the sense that there is a certain sense of what I would call randomness about it,” King said in an interview for ‘Going for 55: Rangers’ Journey Back to the Top of Scottish Football’. “Not to be too philosophical, but that is something I believe in life. Life is very random and it is how you deal with events as they pass you by that makes a difference.

READ MORE: Kevin Muscat: What it's like working with Rangers manager candidate

“Towards the end of the conversation, I asked him if he had been missing playing and that side of things and he said yes and that he was really missing the buzz and the thrill of being there at three o’clock on a Saturday, European nights and just the buzz of the game. I asked if he was thinking of going into management and he said that is where he saw himself going next. Then I very casually said ‘Oh, that is interesting to know, we might give you a phone call one day’ and it was a very casual, if you want to say flippant, comment from me.”

The rest, as they say, is history. King knew he had to deliver a winner, a man who was befitting the office and the institution. If Gerrard had failed, he could well have taken King down with him and that sub-plot is perhaps part of the story once again as supporters critique every key individual from the dressing room to the boardroom.

The considerations for Bennett and Bisgrove in recent days will have covered several areas. Many questions have been asked of those who have been seated across from them, but each interview will have provoked queries of themselves and what they have been looking for in a manager.

There have been many facets – from previous success and tactical approach to the development of players and a record in the transfer market – that have had to be considered from a professional perspective. The personal touch has to come into it as well.

“I would say it is the same as recruiting any senior figure or manager,” was another point made to the Rangers Review as the relationships with staff were highlighted as an area that is perhaps overlooked but one that permeates throughout the club. “How is their body language, their demeanour, their manners, their decency to people? Do they get people onside? Do they make people happy? Do they create a good atmosphere around the place? If you look at any top manager in any industry, that is what you will find. That, to me, is as important as anything.”

When it came to Gerrard, those qualities were instantly appreciated. The Liverpool legend had an aura about him that commanded respect but a way of inspiring those around him that ensured players, staff and supporters would go with him on the journey. If it had not ended when it did, recent history would have been very different.

King only discussed the deal for one of his Anfield icons with two people. Mark Allen, then the director of football at Ibrox, was tasked with putting the move together, while counsel was sought from boyhood hero turned close friend Kenny Dalglish. Once initial considerations over Gerrard’s lack of managerial experience were talked through, King pressed ahead on a plan that would transform Rangers on and off the pitch.

“We tried to do this over a short period of time because there was a concern with the media and Steven didn’t want a situation where it was announced that he was a potential target and he turned it down or we turned him down,” King said. “That would have been awkward for both. We kept it tight and then got him up to sign a contract. It was still confidential at that point, but I flew in for the signing and Steven drove in and people knew that Steven would be Rangers manager.

READ MORE: Philippe Clement: Rangers manager candidate assessed by Thomas Buffel

“That day was actually quite phenomenal because Steven arrived and signed and the crowds built and built. There were 50 people, 200 people, 1000 people, 2000 people and eventually Police Scotland got hold of our security and said we had to open the stadium and let people in. I think around 7,000 were there and we had the signing, did the media and then took Steven down and around. I tell you, that day, if Steven didn’t really understand, which I think he did, what Rangers meant to the supporters, the welcome he got that day was just unbelievable. When he came back in, he said to me ‘Wow, what a buzz. Can I do that again?’ He was genuinely blown away.”

Once the seats are taken in the Blue Room, there is no going back for either party. The walk through that famous, much-photographed door is a step into the unknown, one where neither the manager nor those that have put him in place can be sure of what will follow.

Van Bronckhorst was flanked by Ross Wilson, the sporting director, and managing director Stewart Robertson as he returned to the club. A year later, those same figures sat alongside Beale. Just 12 months on, Rangers will set up the table once again as the portraits of the greats of yesteryear loom overhead, almost casting judgment on those who have Rangers’ future and fortunes in their hands.

The man in the middle is always the one that changes but the two on either side of him will be different on this occasion as well. For Bennett and Bisgrove, that gathering in the Blue Room will mark the end of a process but the beginning of an era.

It is one that will define the coming years for Rangers, one that will determine their own standing with the supporters. The 19th manager must deliver the 56th title. Once pen has been put to paper, then the pressure will really be on.