When it comes to football on the island of Ireland, there isn't much 102-year-old Charlie O'Leary has not seen or done.

From serving as the Republic of Ireland's kitman at two World Cups and a European Championship, to refereeing behind the Iron Curtain, the Dubliner has an almost legendary status.

What is not as well known is his involvement in founding the "street leagues", which helped hone the skills of some of the best players in the history of both the Republic and Northern Ireland.

Now his story is the focus of a new film which will premiere at the Dublin International Film Festival on Tuesday.

As the Republic's kitman, O'Leary was part of the national team setup during its golden era, when Ireland defeated England in Stuttgart at Euro '88 and famously stunned Italy in New York at World Cup '94.

But his influence stretches to some other iconic moments thanks to the street leagues, which he founded in East Wall in Dublin in 1945.

Charlie suggested to the local priest the idea of using the parish church's juvenile sodality - a religious group for young parishioners - as the basis for a football league.

The sodality was organised on the basis of the local streets - and so the street leagues were born.

"Schoolboy football hadn't been organised and there was nowhere for a young boy around 14 if he wanted to play football," Charlie said.

"At least this gave those kids at that age a chance of representing those roads in football and getting them interested.

"So we formed the leagues and they really cottoned on."

So much so that by the 1950s the leagues had spread across Dublin and then to cities across the island, including Belfast.

The leagues first took root in east Belfast, where people associated with the Harland and Wolff shipyard were among the first to compete.

They began to feature young men who would go on to achieve sporting greatness.

In the Republic they included Tony Dunne, who won the European Cup with Manchester United in 1968, Liam Brady, winner of the FA Cup with Arsenal and two Serie A titles with Juventus, and Johnny Giles, part of the great Leeds United side of the 1960s and 70s.

In Northern Ireland, at least three of the 1958 World Cup squad spent time in the street leagues - Harry Gregg, Bertie Peacock and Jimmy McIlroy.

In later years Manchester United's Sammy McIlroy - who went on to manage Northern Ireland - and Jimmy Nicholl, current Northern Ireland assistant manager, took part in the leagues.

There was an early sign of things to come in 1957 when Republic of Ireland B took on Romania B in Dublin.

"There was Liam Tuohy of Newcastle, Noel Payton of Leeds and Dickie Whittaker of Chelsea, all three of them standing together, shoulder to shoulder, for the national anthem," Charlie said.

"Each of those had played, you could pull a curtain over where they lived, the houses were that close.

"On one day they represented Ireland and all played in the street leagues."

Charlie was born just a few months before the Irish Free State - as it was then known - played its first international football match.

The story of his life - which has therefore spanned the entire existence of his country's national team - will be shown in The Charlie O'Leary Story - From Johnny Cullen's Hill to the Olympic Stadium Rome.

Fergus Dowd, who produced the film along with Joe Lee, said the street leagues gave opportunities to young people who would not otherwise have had them.

"One of the players said to Charlie it was like playing for your country, you played for your street but you were amongst friends and it was really community based," he said.

"I think in a sense we've really sort of lost that innocence - these kids had a jersey on, they were representing the road and their mothers and fathers were watching, so it was a massive community event.

"Nowadays a lot of the clubs here have their own academies whereas this grew very much organically and it was down to Charlie's idea of making it happen."

The leagues persisted into the 1970s, giving an opportunity to the man who delivered Northern Ireland's greatest moment on the world stage, Gerry Armstrong.

A few years after his iconic goal sealed a 1-0 victory against hosts Spain in the 1982 World Cup, it was the turn of the Republic of Ireland to revel in a shock victory.

They defeated England 1-0 in Euro '88 and Charlie was watching from the dugout, having been appointed kitman two years earlier.

"I saw grown men cry," Charlie said.

"There was a man who used to live next door to me and he had gone with his son and he came over to me and he was sobbing.

"He said 'Charlie, I can boast, I was here when we beat England'."

Six years later there was another iconic win, this time against Italy at the World Cup and again, Charlie was there.

Those great victories were masterminded by Jack Charlton, who Charlie said was the best man manager he ever worked under.

He recalled one occasion when the boss quizzed him after some players were involved in a "drinking session" the night before which had ended in a "rumpus".

"He said 'I'm asking you a simple question, what happened last night?'," Charlie said.

"I said 'boss hang on a second, if I tell you then you're involved and you've got problems to resolve.

"I tell you what I'll do, if I say to you everything is resolved, then it's all resolved.

"So Jack said, 'that's all I want to know, we'll leave it at that,'

"I got away with that gag every time there was a problem."

From being part of the backroom team for those famous victories to refereeing in East Germany during the Cold War - "a bit frightening" - Charlie has plenty of footballing highlights to pick from.

So what is his favourite moment?

"I have to say, I'm a Roman Catholic, when we went to Italy [for the 1990 World Cup] we were brought to see the Pope," he said.

"I was frozen, I couldn't speak.

"People say, I said this and I said that, I don't remember saying that.

"But that to me was the biggest thrill I ever got in my life."