THEY were fierce rivals an opposite sides of the Old Firm divide who gave no quarter whenever the great Celtic and Rangers teams of the 1960s and 1970s they captained clashed at Parkhead, Ibrox or Hampden.

Yet, they were also team mates together with Scotland who combined forces to devastating effect on numerous occasions to help their country record some famous victories, most memorably against England.

And away from blood and thunder of their onfield encounters, they were close friends, kindred spirits with the same loyalty to and love for their respective clubs who had an enormous admiration for each other both as people and players.

John Greig, the great Rangers skipper, was deeply saddened to learn of the passing of Billy McNeill, his legendary Celtic counterpart, at the age of 79 earlier today.

He paid an emotional and highly personal tribute to a man who, like him, has had a statue erected in his honour outside the ground that he plied his trade at as a professional.

HeraldScotland:

READ MORE: John Clark and Bertie Auld reflect on passing of fellow Lisbon Lion Billy McNeill

“I knew Billy hadn’t been well for a while, but it is still a big, big shock when the inevitable happens,” said Grieg. “He was such an icon, such a big, big man. I keep picturing him in his playing days.

“Because we were both Old Firm captains, we were asked to do a lot of public engagements together. In the west of Scotland they don’t like bringing one person from one team. So they always asked the two of us. To such an extent, in fact, that we both got our doctorates from Glasgow University together on the same day.

“My wife and I got to know his wife Liz as well over the years and it is Liz and the family who I obviously feel sorry for today. They have known Billy has been unwell for a while, but it is sad when it happens.”

Edinburgh-born Greig first encountered McNeill after breaking into the Rangers team in the early 1960s and enjoyed by far the better of his early encounters with the imposing Celtic centre half.

However, when Jock Stein was appointed manager at Parkhead in 1965 he turned the East End club, with no little help from his Bellshill-raised defender who he forged a strong relationship with, into the dominant force in the country and indeed in Europe.

HeraldScotland:

READ MORE: Archie Macpherson: Billy McNeill was a legend but I'll always treasure his input as a broadcaster

Greig, who was voted the Greatest Ever Ranger in 1999, had the utmost respect for McNeill, who was named as the Greatest Ever Captain of Celtic in 2002, and admitted he much preferred playing with him with Scotland than against him.

"We weren’t friends on the park, but we had a mutual respect for each other," he said. “Billy was hard man to play against because of his stature. He was over six feet tall and he was quite an athlete.

" He was obviously a very important player in a very good Celtic team. He was a centre half and most clubs build their team around their centre half. He was a leader. He used to score so many goals from set pieces. Billy was like an extra forward because of his aerial ability."

Grieg added: “In those days, the Scotland team would probably comprise of 50 per cent Celtic and Rangers players. A lot of people didn’t understand how we could get on with each other. But we played for the national team together. We had respect for each other as football players.

HeraldScotland:

READ MORE: Andy Walker: Billy McNeill was a family friend for life and an inspiration to the end

“Remember, in 1967 when Celtic won the European Cup Rangers played in the final of the European Cup Winners’ Cup a week later. That was the standard of the players that Rangers and Celtic had. That is why the national team used to comprise so many players from the Old Firm clubs.”

Greig and McNeill managed Rangers and Celtic respectively after retiring from playing and faced each other in the dugout on numerous occasions between 1978 and 1983.

But the considerable demands and pressures of being the public figureheads of the Ibrox and Parkhead clubs didn't impact on their relationship.

“Billy and I became good friends away from the football," he said.

“He was a gentleman. Billy was respected because he was a really decent guy. He conducted himself in a great way. He was always a great advert for Celtic Football Club.

"He will not be forgotten by a lot of people, especially the Celtic supporters.”