"The old ballad singer used to carry the news," says Christy Moore, neatly explaining his life's mission in the two-part documentary Christy Moore: Journey (RTÉ One, Sunday, Monday).

“I like to think that songs carry a different version of the news than they get from RTÉ or the Sunday Independent or the Sunday World.”

And so the Newbridge bank clerk, who escaped to London in the 1960s and learned from Ewan MacColl that folk songs could be political and have a relevance, has spent a long and enormously successful career.

Moore has filled a songbook with powerful, conscience-pricking storytelling on a vast range of political subjects, motivated by a need to draw attention to inequality and injustice.

In his own songs, Moore describes himself as a “bogman” or an “ordinary man”, but the man we meet in the two-part biographical documentary is a serious man, an activist whose weapon is a guitar, a conviction musician, and that makes for a particularly serious two-hour documentary, shown over two consecutive nights.

The opening moments are classic musician biopic shots: a camera follows Moore, trailed by his small backing band, as he wends his way through backstage corridors before arriving on stage before a hall filled with 3,000 eager fans.

And there are further glimpses of his touring world; Journey was filmed over a five-month touring period, with a reminder that Moore has been on the road for 50 years.

But viewers tuning in for more than snippets of his legendary concerts are disappointed: Journey is all about the songs, focusing on some of his best-known songs and exploring why he wrote them, mostly through close-up interviews in Moore’s home studio.

And so, while “don’t forget your shovel when you want to go to work” is the sort of catchy line that is a sure-fire belter when delivered by the audience at his concerts, it gets poignancy and a return to its original meaning in Journey when played beneath archive footage of the reluctant army of Irish emigrants, the overworked, underpaid, socially unmoored Irish navvies in London in the 1960s.

It goes on in similar style: song, archive, explanation – giving the backstories to his H-Block songs, his one on the Stardust tragedy, the abject tragedy of Ann Lovett’s death and his Carnsore protest ballad, the song in support of the Dunnes Stores anti-apartheid strikers, among many, many others.

With this approach there was never any way this film, directed by political documentary maker Mark McLoughlin, could, for anyone other than dedicated Moore fans, have been an easygoing Sunday or Monday night watch.

And while Moore reminds us that some of his songs have been banned on RTÉ, that he got hate mail over the Ann Lovett song and that he endured negative media commentary for his fundraising support for the Republican movement at the height of Troubles (he believes a united Ireland will happen), it is probably true to say that at this stage in his long career Moore is more national treasure than thorn in the side of the political establishment.

Alcoholism

Towards the end of part one he talks with searing frankness about his alcoholism and how embarrassed he is now listening back on those recordings when he was drunk or stoned. He has, he says, been sober for 25 years now.

Hearing that put a darker spin on his other guaranteed crowd-pleaser, with the line about how “yer man stayed up on the surfboard after 40 pints of stout”.

In the second part of Journey he talks about his breakdown 15 years ago, acknowledging it is still difficult to talk about; at the time, he says, he couldn’t say no to a huge range of commitments and was exhausted through overwork.

“I really could just communicate with Val and our young ones, and I didn’t play for two years.”

A viewer coming cold to the Christy Moore story would be right to wonder, “Who is Val? How many young ones?”, but this film gives only so much in terms of biography – and most of it is about his early years growing up in Newbridge.

“You can’t be funny all night, you can’t be sad all night . . . but you can do all of those things in the course of two hours,” says Moore, describing his concerts.

But as this two-part film focuses on the stories behind the songs – and Moore doesn’t do moon-in-June silly love songs – there’s not much light relief, except towards the end with the scene in the magnificent Royal Concert Hall in Glasgow where he belts out a joyous I’ll Tell Me Ma/Lisdoonvarna mash-up.