Having previously never been further west than Mizen Head – you may recall their cocaine spotting holiday in the original 2016 Young Offenders film – a trip to Bogotá results in Jock Murphy being detained at the Colombian president’s pleasure and Conor MacSweeney managing to get back to Cork where he’s also slung into jail.

Fast forward three years and Jock is still rotting in his Colombian hell-hole while Conor is out of clink but having to deal with the quadruple horrors of Sgt. Healy becoming his stepdad; Linda ditching him for the human weasel that is Gavin Madigan; Billy Murphy wanting to be his new bezzie; and getting grinds from ex-Principal Barry Walsh to pass his Leaving Cert.

“The first episode is go, go, go, it doesn’t give you a chance to sit down,” says Alex Murphy who bares more than a passing resemblance to Conor. “There’s a lot of updating that needs to be done and then it’s the usual mayhem with maggots in people’s underwear and fish hooks getting stuck in their mouths.”

Due to other work commitments, Chris Walley, AKA Jock, only features fleetingly in the early episodes with Conor left to do the heavy lifting.

“I’d hate people to see this series and think that me and Chris have fallen out in real life,” Alex resumes. “We’re still best friends and he’s currently living with me as he prepares to do a play in The Abbey.

“The big question for Conor is how does he survive without his brother figure? The answer at first is ‘Badly’ but then comes his unlikely bonding, via-a fishing trip, with Healy who’s getting it in the ear from Mairéad to be nice to him. In the first three seasons Healy’s just Robocop, this one goal guy but there’s more to him than you might think.

“What Peter (Foott, Young Offenders screenwriter) is so good at is in the first two minutes setting up the problem in the house and then by the end of the episode you have a nice solution – or can see the reason why people are the way they are. That episode has such a good circle.”

And a brilliant guest turn from Pat Shortt who’s rarely been Pat Shortt-ier.

“Yeah, Pat’s great and a real scene-stealer,” Alex nods. “This new season as well there’s a good bit more of Billy Murphy, Fake Billy and Fake Fake Billy. Shane Casey is one of my favourite actors. You just never know what he’s going to do. He’s such a kinetic performer – the way he waves as the character is so mental but you buy it. Like Uncle Colm in Derry Girls, you remember Billy as being in every episode when in fact he’s the supersub coming off the bench. Without giving too much away, there are a couple of real tearjerkers where you get to discover why Billy is like he is.”

The one downside to playing Conor is that high and tight haircut of his. Does Alex dread the ritual sacrificing of his curls?

“It’s a curse and a blessing because now that my hair’s longer people automatically go, ‘You’re such a transformative actor!’” he reflects. “I’d love to think I’m Sean Penn or Robert De Niro but, no, it’s the haircut. I actually love it because when you get the head shaved every day and put the tracksuit on, it’s your armour and you just feel tougher.

“The curse is that for eight weeks you’re not getting into any pubs or clubs with that haircut, especially in Cork!”

Young Offenders - Series 4. Sgt. Tony Healy (DOMINIC MACHALE);Mairéad MacSweeney (HILARY ROSE);Linda Walsh (DEMI ISAAC OVIAWE),BBC/Vico Films

SPOILER ALERT! The new season’s second episode features a brilliant turn from David McSavage as the examiner coerced by Gavin Madigan, now a teacher at St. Finnan’s, into making sure that Conor blows his Irish Oral. Pun intended.

“He’s another who on the day could do virtually anything when the camera’s running,” Alex says. “For the first few takes he was kind of holding back but eventually he just fucking let go and I was like, ‘Yeah, that’s what we need, 100% McSavage!’ In between takes he vaped and I said, ‘Oh, can you blow the biggest vape cloud into my face?!’ Otherwise the facial expressions and noises he makes to put Conor off were all improvised. I’m very proud of that episode.”

As well he might be. In a previous interview, Alex told us that Conor and Jock pissing on Principal Walsh’s shoes held the record for most reshot Young Offenders scene due to cast members corpsing. Has anything bettered it since?

“There’s one where Healy’s interrogating the boys and Conor does that thing of talking gibberish in a really strong Cork accent, which makes Healy go, ‘What did you say, what did you say?’” he smiles. “There’s something about his annoyance levels going up and up and up that makes it impossible not to laugh.

“It’s the same with any scene that PJ Gallagher’s in. He’s the best actor at portraying stress I’ve ever seen. His skin vibrates. The last Christmas special when he’s trying to put the seatbelt on – ‘Ya fackin’… aaaarrrrghhh!’ – is one of my favourites but almost too uncomfortable to watch.”

Rarely in televisual history has there been a toerag as odious as Gavin Madigan.

“Doing scenes with Gavin is great because everything’s a competition. It’s, ‘I’m going to get out the door first – or will I be the bigger man and let you go out the door first?’ I get taller when I’m acting with Danny Power, who plays Gavin and couldn’t of course be nicer, because we’re constantly trying to outdo each other – especially when Linda’s around.”

We’ve fellow Corkonian Cillian Murphy to thank for the 16-year-old Alex deciding he wanted to be one of those actor fellows.

“My dad pointed out watching The Wind That Shook The Barley that, ‘He’s from Cork’ and I was like, ‘Oh, very good.’ Then you watch Batman Begins and go, ‘There he is again. How’s a bloke from five minutes up the road – he’s Ballinlough, I’m Douglas – playing Batman?’

“The big turning point came when Cillian was doing Ballyturk in the Opera House and I sent them an email saying, ‘Hiya, I’m an actor and I’m hoping to audition for college next year. I’m a big Cillian Murphy fan, can I meet him?’ I left my number at the bottom and then the night I went to see the play there was a text on my ‘phone saying: ‘Cillian is happy to meet you afterwards, go up to the bar.’

“So I go up, bump into Stephen Rea who’s also in the play – ‘It’s Cillian I’m here to see, Stephen, but nice to meet you too’ – and then get to meet Mr. Murphy who’s very personable and tolerant of this bumbling teenage idiot. I’ve met him sporadically since and he’s always been friendly to a fault.”

Alex Murphy. Copyright Miguel Ruiz.

If recent Irish comedy hits like The Young Offenders, Derry Girls, The Lovers and Bad Sisters have anything in common, it’s their refusal to water things down for international consumption.

“Definitely,” Alex nods. “The Young Offenders is a very local show that comes from humble beginnings. We made the original film for no money and just seven or eight crew, not knowing if it’d even be in the cinema. To see the reception it then got at the Galway Film Fleadh, and how it’s skyrocketed since has been unbelievable. The worry when the BBC came on board was that they’d want to rein it in a bit for that wider audience but, no, they’ve left us alone. Rather than shying away from them like they might have done in the past, people are attracted to cultural differences – and the exotic new swear words they can learn from them!”

Do the BBC, who stump up the lion’s share of the Young Offenders budget, leave them to their own devices whilst filming or come over to Cork to check on their investment?

“Yeah, they’d visit once a season,” Alex says. “You’d think they’d come during a nice monologue or great emotional scene, but, no, when they arrived I was humping a fish for three hours! When we did that tuna episode, it was a real tuna we were filming with for about a week. Every day it got more and more horrible. So I’m there stinking of rotting fish as a guy from the BBC says (puts on English lovey accent): ‘Brilliant work Alex, I love what you did there!’ I’m like, ‘Thank you very much!’ The tracksuits fucking stank for ages afterwards. The things we do for our art…”

With Conor and Jock both banged up, Alex had time last year to play Philip in Conversations With Friends, directed by Lenny Abrahamson – who he absolutely loved working with.

“I couldn’t get over Lenny being so personable. He doesn’t have to be as nice as he is. Even when I wasn’t needed, I spent a lot of time on set just watching him direct and seeing how it all works. If there was a day-player coming in to do a scene, he’d go over, say, ‘Welcome to the set, I hear you’re from Thurles. Do you know so-and-so from there?’ and make a connection. You see him just mellow people out. He’s very skilful in that regard.

“Lenny’s been very good to me,” Alex adds. “People often say, ‘Let’s meet up for a coffee’ but he did. As an actor you worry about doing the right thing and being in the right place – ‘Should I go to London or do I need to be in LA?’ – and he just said, ‘Are you happy, are you working? Chill out, you’re doing okay.’”

Young Offenders - Series 4. Conor MacSweeney (ALEX MURPHY). BBC/Vico Films

Alex also had a blast shooting Spud, the recently premiered short film that Siobhán McSweeney wrote, directed and stars in, and which also features Dermot Crowley, Aisling Kearns and Mary Coughlan who’s as impressive in front of a camera as she is a microphone.

“I missed it the other day on TV, so I’ve yet to see it,” he admits. “It was a one-day shoot in the UK somewhere – I found out shortly afterwards that I had Covid, so that’s probably why I don’t remember much about it – but it was a lot of fun. Siobhán got funding from the BBC to make her directorial debut and it was brilliant. She knows what she wants and she got it. I’m interested in going that route myself sometime so, like with Lenny, I was making mental notes.

“The other great thing about Spud was getting to appear alongside Mary Coughlan who’s just this force of nature.”

That she is. Adding to an insanely busy last twelve months is the Irish language cold case TV series that Alex just finished shooting in Gweedore.

“It might change but right now it’s called Saor Sin Ó Olc, which is Deliver Us From Evil,” he reveals. “I wasn’t brilliant at Irish in school, but I got the part two months prior to shooting and was able to do enough prep to play a Garda sergeant as Gaeilge. There were lots of proper Gaeilgeoirs in it like Dónall Ó Héalai – I’ll trust you to add the fadas! – who gave me a dig out from time to time. It was the most fulfilling nine weeks ever and means that I was able to speak a bit as Gaeilge with the Kneecap lads at the IFTAs.”

Is he a fan of Messrs. – and, indeed, messers – Chara, Bap and Próvaí.

“Yeah, big fan,” Alex nods. “They’re funny but also really intelligent, which you need to be doing what they do. It was a really celebratory night with Cillian winning Best Actor. I was there with Demi (Isaac Oviawe) to present Peter McKenna with his Script Drama award for Kin, which made me really stressed. I don’t normally get that nervous but you’re there backstage thinking, ‘I’ve got to go up on stage as myself and haven’t prepped’, even though there’s nothing really to prep. You just don’t want to make a complete balls of somebody’s career highlight to date.”

Finally, what – and there several gazillion to choose from – are Alex’s all-time favourite The Young Offenders moments?

“I really enjoyed Conor getting to sing Aslan’s ‘Crazy World’ in the pub,” he shoots back. “It was a whole day of me with the track in my ear going, ‘I want to make it as real as possible!’ I’m really not a singer but the finished scene was great.

“I also loved the episode where we sang U2’s ‘With Or Without You’ at Jock’s Mam’s graveside,” Alex concludes. “We were shooting that in Cork and I was happy because six graves up was my grandad. I was like, ‘What a lovely, bizarre fucking moment!’”

• Season Four of The Young Offenders airs on Fridays on BBC One, at 9.30pm.