It was the story that rocked the football world to its foundations — and it was brought to you by the Belfast Telegraph.

The July 10 1989 edition of the Belfast Telegraph which announced that Maurice ‘Mo’ Johnston (pictured left in a Celtic jersey) had done the unthinkable by joining Rangers

These days, a Catholic player signing for Rangers is commonplace and wouldn’t raise an eyebrow, even within Glasgow’s notoriously volatile ‘fitba’ community.

But it was a completely different story exactly 20 years ago today when a certain Maurice John Giblin (‘Mo’) Johnston put pen to paper at Ibrox Park — and lit the blue touchpaper virtually everywhere else.

Graeme Souness, the Rangers manager at the time, had always said that if a player was good enough to wear the shirt, it wouldn’t matter what his background was.

Even so, no-one expected his first Catholic capture to be a man who had forged his reputation with bitter cross-city rivals Celtic, and took great delight in expressing his Catholicism to the ‘Teddy Bears’ fans during Old Firm clashes.

Add to this the timing — two days before the ‘Twelfth’ and during a period of continuing sectarian strife both here and in Glasgow — and you could imagine the searing heat generated by the French-based Scottish international’s shock move.

The Belfast Telegraph sports desk had been tipped off about the story very early that morning — and even we found it hard to believe.

But our informant had always been trustworthy in the past and — without any confirmation from Rangers or Johnston’s agents — we ran a story in our first edition that the Scottish champions were about to sign the player in an audacious £1.5m transfer.

Within an hour of the newspaper hitting the streets of downtown Belfast, a group of angry loyalists had gathered outside our Royal Avenue offices, demanding that the story be ‘retracted’.

Our switchboard was also virtually jammed with furious callers complaining that the Telegraph was deliberately stirring up sectarian tension in Northern Ireland by printing such a ‘fairy story’ so close to the Twelfth.

But by mid-afternoon Rangers had confirmed what was at the time, and arguably still is, the most controversial capture in British football history — and when the Telegraph’s final, updated edition rolled off the presses that day, the ‘fairy story’ was accepted as being very real indeed.

It was a development that left both Rangers and Celtic fans reeling; the Hoops had themselves been hoping to re-sign the nomadic Johnston from French club Nantes.

The player had even publicly stated his desire to rejoin the Parkhead outfit, for whom he had scored 55 times in his previous three-year spell.

It was clear, therefore, that the Bhoys would never forgive Mo for this ultimate act of footballing treason; the main question was, however: would Gers supporters accept him after 116 years of following an almost exclusively all-Protestant club?

There were demonstrations, and some dyed-in-the-wool fans burned both their scarves and season tickets and vowed never to return to Ibrox.

But most Rangers fans decided to give Johnston a chance, and he repaid their faith by helping to deliver two championships and scoring 46 goals in 100 or so games — including, almost inevitably, an Old Firm winner against his former pals.

Johnston later joined Everton and now, at the age of 46, is director of football at Canadian club Toronto FC — which could not be further removed from the bitter, divided Glasgow.

Speaking earlier this week, Souness recalled the day he turned Scottish football upside down in 1989.

“There was an element of mischief in it,” he admitted. “I believed we were hurting Celtic by signing him.”

Souness added: “Every Rangers manager had said in the past that they’d sign a Catholic, but I meant it.

“I was married to a Catholic, my children were Catholics. Religion was never an issue with me.”