It is 7pm on RTÉ’s Lyric FM on Monday, September 4th, and something seems a little off on the classical music station.

From the speaker a gentle guitar strumming makes way for Johnny Cash’s voice introducing Mystery Train, "with my friend John Kelly". After an eleven-year hiatus, the cult music show is back on Irish airwaves.

The opening track is a smooth funk number and the song’s lyrics outline a rough ethos for the show:

"… Everything I do gonh be funky from now on, yeah," sings Lee Dorsey. "I just be myself and do my thing/ A little soul can’t do no harm… / So go with me if you can…"

With that gruff Enniskillen accent, John Kelly tells us that that sentiment is loosely the script he’s working off while playfully queuing the theme tune for Mission Impossible.

"The last time I did Mystery Train, I didn’t have grey hair and I wasn’t wearing glasses. But then, I was probably half-cut as well," he tells listeners, chuckling. "So it’s all good…"

"The best radio programmes are the ones that are informed by a musical curiosity that works both ways."

Mystery Train was axed in 2006 in what was a major overhaul of the RTÉ Radio schedule as music and arts shows were cut in favour of more 'speech-content'. For the intervening decade, Kelly had a popular afternoon slot on Lyric FM called The JK Ensemble, yet plenty of people are convinced that this is a return to radio for him.

When the Train was last on the tracks its home was on RTÉ Radio 1. Aware of the new surrounds - and the sensibilities of the hardened classical folk he’ll have to win over - Kelly issues a warning to "lock all the doors" before he plays a song from LCD Soundsystem’s new album, American Dream.

There is no doubt we are careening into strange territory for these coordinates on the dial as rolling drums beats and synths build and spill loudly from the speakers during change yr mind.

"I’ve been thinking a lot about the Irish-American Diaspora of late. You know, Kelly-Anne Conway, Sean Spicer, John Kelly," he pauses to register his namesake. "There are quite a few of them. Steve Bannon, and these sorts of people. But then there’s James Cagney, Gene Kelly, and there’s that guy: James. Jeremiah. Murphy. A lot has happened in eleven years…"

David Bowie’s Blackstar follows. It can be heard as a nine-minute lament for the musical void left behind by departed artists. Simply too many to name since the show last aired, but listeners are assured that as many of their songs as possible will be played over the coming weeks and months.

This first night Kelly is feeling his way back into his comfort zone, blowing off the cobwebs, somewhat bashful at the outpourings from old fans of the show. But by Sunday, he is well in the groove and demonstrating why Mystery Train had a reputation for being the most eclectic slot around.

Throughout the week you heard Bowie, Beck, Lisa O’Neill, Herbie Hancock, Arthur Russell and Allen Toussaint; a series of Rolling Stones covers one night, and five consecutive James Bond tunes the next.

Author Kevin Barry brings things to a close on Sunday night with his selections: Liam Clancy, Lee-Scratch Perry, Kate Bush, the Beatles (Barry wrote a novel called Beatlebone recently with John Lennon as his main character) and some Detroit techno from Derrick May. Listening, you can’t help but crack a smile.

"I can’t play The Clash at two o’clock in the afternoon on Lyric. That’s not why people are tuned in. But there is a psychological thing about seven o’clock at night."

"It is like the computer is not up to speed yet," says John Kelly, when we meet on a shrinking Montrose campus. "I’m having to think about things… I play a piece of music, and I’m like, I must play such and such after that. But what’s it on…? I know I have it on a compilation, but what’s it called and where is it? Whereas when I was in the thick of it I could just grab things quickly.

"But it is thoroughly enjoyable. Once I got up and running, as soon as I put on the first track, I felt I’m home now. This is what I do."

Kelly is relaxed and engaging as we chat away about music and how it feels to be back presenting Mystery Train.

"If I get to where I was there’ll be a lot more improvising, free form, you know. When I’m on top of where everything is, and if it occurs to me with twenty seconds of a disc to go, oh god, there’s a couple of notes there that sound just like A Day In The Life. I need to be able to know where A Day In The Life is and get it on.

"I enjoy doing that live performance element… Slightly seat of the pants stuff. Now I’m not trying to elevate what I do to what a jazz band does, or a musician, or a club DJ. It’s not that level of skill, by any means.

"But halfway through a song I might hear a couple of notes, I might hear a solo, and I know I have something by him… Or I’ll know what would be brilliant off the back of it."

Music is something that fascinated Kelly from the start. It was the exposure he got through the regular places like Top of the Pops and other such shows that hooked him. It became a constant curiosity that he nurtured.

"When I was a teenager I listened to Van Morrison a lot. And if you pay attention to his records, the names that are mentioned, the covers that he does, the references to Lead Belly and Hank Williams and Muddy Waters, I was the kind of kid who would go down those roots and explore it further. But it all started from somewhere. You are not just born knowing this stuff. You have to investigate it and suss it out. You have to be enthusiastic.

"In those days they made television shows about music… There’d be an Arena documentary on Billy Holiday… a documentary on John Coltrane. I remember watching those.

"Which is why I get annoyed when they talk about arts programmes as if they’re for weirdoes. I was just a kid watching the Telly! Could change your life when you see something like that."

With changes coming down the tracks in Lyric as a result of people retiring, there were opportunities to play around with the schedule. After a number of conversations with his boss, Aodán Ó Dubhghaill, the head of Lyric, it became clear what they were discussing.

"I used to say all the time, look Aodán, it’s a classical music station. He’d say, ‘No, it’s a music and arts station…’ What we’re talking about here is really the programme I used to do. And if I’m going to do it, call it Mystery Train. Because I’ll know what it is, you’ll know what it is and there’s plenty of people out there who will know what it is… There’ll be no worries about what’s appropriate on Lyric."

Every radio station should finish its night with Donal Dineen…

The JK Ensemble has been replaced in the afternoons by classical concerts. Then 7pm comes and things change, why is that?

"People used to say to me why don’t you do what you used to do? And I say, it’s inappropriate. It would be disrespectful; I can’t play The Clash at two o’clock in the afternoon on Lyric. That’s not why people are tuned in.

"But there is a psychological thing about seven o’clock at night. It’s like a watershed. It is hard to explain to those who aren’t into music and who probably just think I’m coming on and playing a bunch of rock records… But Aodán understands; he gets what Mystery Train is. And it’s basically a music programme for people who are interested in music.

"People watch Jools Holland and all sorts of stuff. They watch it because they like the programme and they trust Jools Holland. So if he brings on a hip-hop act or a grime act, or whatever it is. You go okay I’ll check this out. There’s an element of trust involved."

Like a gatekeeper?

"Well, that sounds a bit too controlling… It is more a curator, a guide… Because what has changed is that there is so much music out there. It can be a bewildering place in which to find new music…

"There is an idea out there now that because there is so much music available online at the touch of a button, that this removes the necessity to have a mediator or a curator around the place. I don’t think that’s true.

"You still need your BBC 6 Music… You need programmes like Mystery Train, and others that we have on Lyric, and Dan [Hegarty] and Cathal Murray… Every radio station should finish its night with Donal Dineen…

"There are loads of people doing good stuff, but we’re all on different stations. But I suspect that is being looked at. There’s a lot of talk about content at the moment, if it means anything surely it has to mean looking at those possibilities."

With the amount of music available these days, the need for trusted places to go for direction is more important than ever.

"That thing about saying all this music exists and everybody can get it. That is like sending someone into the law library, and they’re not a lawyer, and saying these are the books but they don’t know where to look. You don’t know what’s in them. You still need someone who knows what is in there…

"Music is all about communication… A radio programme, when it works, is about sharing and discovering things… The best radio programmes are the ones that are informed by a musical curiosity that works both ways."

As we wrap things up and Kelly is walking towards the radio building, he turns to check something. "You won’t get me in trouble now, will you?" he says, cracking a smile as he heads off to play some more records.

Mystery Train, RTÉ lyric fm, Monday-Thursday at 7pm, with a special edition on Sunday at 7pm - listen to the most recent edition here.