With the London 2012 games fast approaching, the pair were two leading lights on a Team GB squad hopeful of making a real impression that summer.

The training schedule for those on the squad at Sheffield's English Institute of Sport was tortuous. Campbell and Joshua, the bantamweight and super heavyweight hopefuls, still decided to make the 10-minute stroll down to McDonald’s one lunchtime.

No sooner than they sat down to eat, they noticed a car pull up in the drive thru. A beaming face looked at them through the window and waved. The door opened and out clambered all 6-foot-9 of Tyson Fury.

The newbie pro was a familiar face for both GB boxers, having trained on England squads with Campbell and famously sparred Joshua at Finchley Amateur Boxing Club in 2010. Fury pulled up a chair with the GB boys and talked boxing.

Although the 20-something Fury and Joshua had big dreams in boxing, nobody in the restaurant that day knew that they would go on to win four world heavyweight titles between them and become the two most commercially successful fighters in British boxing history. Nor did Campbell know, as he stood between them for a now-famous snap, that he would be in the middle of one of very few face-to-face meetings between the pair away from the media spotlight.

“It was just a totally random encounter,” Campbell told The Ring. “Me and Joshua are sat in McDonald’s. I don’t eat it nowadays, but back then it was a good cheat meal. It was only down the road from the EIS, so we walked down there. So, we are sat there and Tyson pulls up in the drive thru, spots us and decides to come in. We were just chit-chatting really. I think Tyson was going through a bit of a rough time at that moment, so we were all just talking about boxing and stuff.

“I had been [in] camps with him years before that and was obviously in the middle of training with Joshua at the time, so I knew them both personally. We just had a catch-up and Tyson was wishing us luck for the Olympics and all that sort of stuff. It was all very respectful. I mean, of course I am going to be respectful, I’m the tiniest one there.”

In the photo, Campbell is dwarfed by a fresh-faced Fury to his left and Joshua, cladded out in his GB Boxing kit, to his right.

The Hull man, who went on to claim gold along with Joshua at London 2012, had been a fixture on the international scene for years. A year before Joshua had even walked into Finchley ABC for his first session, Campbell and Fury had both boxed at the 2006 World Youth Championships in Agadir, Morocco.

Fury, a teenager at the time, was drawn to face Azerbaijani super heavyweight Ilham Khatamov in his first fight. Campbell watched from ringside with a couple of teammates.

“I’m there with George Groves and Anthony Ogogo,” Campbell recalled. “And Fury is walking out for his first fight there. Then, all of a sudden, we notice a guy at the top of the arena screaming and roaring, whacking his chest. He has taken his top off and is standing there whacking his chest. I thought, ‘Who’s this guy?’ And they are like, ‘Oh, that’s Tyson’s dad!’ ”

More than 20 years have passed since that tournament on the Moroccan coast. Fury’s next ring walk will take place at Principality Stadium in Cardiff, Wales, for his long-awaited clash with the other heavyweight from McDonald’s that day, Joshua.

Given his history with the pair, Campbell, now 39, is well placed to predict what might happen when they finally fight for the first time December 11.

“Look, this is a fight that could have happened five or even 10 years ago,” Campbell said. “But it is still an intriguing fight. Joshua went down twice in the first round of his last fight against Kristian Prenga, which was quite worrying, but then he came back and knocked the kid out. So, Joshua definitely has that power, but Tyson Fury is a big lump who is awkward and has a good engine. He could make this very difficult for Josh.

“So, they have both got attributes to win the fight. The only way Joshua can do that is by getting into range, letting his hands go and putting the combinations together. But if he falls over his front foot like he was doing against Prenga, that would be a dream for Tyson Fury, to just step back and land a big hook.”

While Campbell is sitting on the fence in his prediction for the fight itself, he has no problem wading into the debate about who has had the better career generally.

“Joshua, for me, has had the way better career,” Campbell said. “I mean, he’s an Olympic gold medalist for a start. Then he’s gone to become two-time world heavyweight champion, too. But they’ve both had incredible careers. I remember even when he was young, Tyson always had that belief in himself. He was always floating around saying what he was going to do.

“So, it has been nice to see him prove himself right because that doesn’t always happen. I’ve seen so many fighters come and go, but Fury and Joshua are still right there at the top after all those years. That picture in McDonald’s was nearly 15 years ago now and look what they are about to do.”