With a father who captained Ireland and played more than 50 matches for his country, cricket was clearly in the blood. Was the intention always to pursue a career as a pro?

Kevin: Not really, I was probably quite late in thinking along those lines. I'd played for Ireland all the way up in age-group cricket but there weren't too many Irish cricketers playing professionally in England - in fact Ed Joyce was the only one. It wasn't until I was about 18 that I realised I might have a bit of talent, then I kicked on and played at the 2004 Under-19 World Cup and never really looked back.

Niall: Not really for me either. When I finished school I wanted to be a professional footballer, truth be told. I probably wasn't as good as I thought I was but I had an offer for a trial at Glasgow Rangers before giving up football at about 16 or 17 to concentrate on my cricket.

Was there much rivalry between the two?

N: Because I was a batsman and keeper and at that stage Kev was just a bowler there was never that direct competition. I was trying to get catches and stumpings off his bowling - chirping away and putting on a silly voice behind the stumps - and he was pulling Darren Gough expressions as he was running in to bowl. He was an opening bowler, and a really good one. We used to call him Shaun Pollock because he looked a bit like him and had that nagging line and length, with that little bit of away movement. But back then Kev was never really one to put in the hard graft. He liked playing the matches but he was more than happy chilling out playing computer games, whereas I was always wanting to get out to the nets or the garden and play.

K: Even in the middle of winter Nialler was always asking me to go down to our club, the Railway Union, and throw him some balls. It was only 500 yards from our house but I could never be bothered. He always got Dad to go in the end.

It must have been unusual for a Dublin family to be so cricket-focused at that time…

N: Yeah, I couldn't tell anyone at school I played cricket. The schools I went to were very Irish schools - hurling, rugby, Gaelic football - and cricket was seen as an English sport. Cricket in the village where we lived was fine but at school you had to keep it on the down low. In my last year I was picked to play for Ireland Under-19s at the 2000 World Cup and the principal announced it over the tannoy. Everyone looked around at me and started giving me quizzical looks. No one even knew I played!

K: Our school was literally in the shadows of Lansdowne Road, so rugby was very popular. We probably did keep the cricket a little bit quiet. A lot of the guys at school came from inner city Dublin and if they knew we played an English game, which was frowned upon back then, we might have been in for a few hidings.

Were you two close when you were growing up?

N: We were always close but when I was about 14 or 15 I wasn't really enjoying school and I was making a nuisance of myself in the village, getting in trouble with the police; whereas Kevin was a good lad and kept himself to himself.

Ireland's magical St Patrick's day in 2007 The 2007 World Cup marked a watershed moment for Irish cricket, as Ireland defeated Pakistan in perhaps the biggest shock in the tournament's history to qualify for the Super 8 stage. In a low-scoring encounter, a partnership of 38 between Niall (72) and Kevin (16 not out) proved crucial as the underdogs chased down their target of 133 with three wickets to spare. K: I was happy to play second fiddle. I was still relatively new to international cricket so I was just taking it all in and trying to stay in as long as I could while Nialler batted so well. It's probably the best he's ever batted in an Ireland shirt. And what a time to do it… N: It's kind of strange when you think of Kev batting like that now [16 from 52 balls] because these days he'd be on 60 or 70. He played the conditions. The wicket was tricky, the ball was doing plenty and it was hard work against a good attack. K: Nialler is full of life when he's batting - wired - and I'm the complete opposite. I just like to chill out. I think he was doing all the talking and I was just telling him to relax. I'm certainly the more laidback of the two of us, in all walks of life I suppose. Sometimes it's a good asset, other times it can be a disadvantage, but I think that's probably why we're so close and why we work so well together. N: It was 2007 when things really kicked off for Irish cricket. It put us on the map and most of the young lads that play with us now - George Dockrell, Paul Stirling - say that watching that match in their living room inspired them to go and play. That's what it's all about.

K: Nialler got in enough trouble for the both of us! There's two-and-a-half year's age difference between us so although we knew the same people, we didn't really hang around in the same group. I was usually sitting at home watching TV while Nialler was out causing mayhem.

N: I remember one time Kev was playing football in the rougher area and got hopped on - he got a few digs - and came home in tears. I went off on my little bike - I had a green bike called Billy - and gave these lads a bit of a kicking. I came back, tapped Kev on the back, and said it won't happen again. Kev was good at school, very well behaved. I was the black sheep of the family, shall we say!

When did you start to knuckle down and focus on your cricket?

N: It was quite strange, really. It took me getting a dog to get me back on the straight and narrow. I asked my parents every day for two years if we could get a dog, and every day they said no. Eventually they got me a golden retriever and it changed my life. It gave me some responsibility: I fed it, walked it, cared for it. It was the best thing I've ever been given in my life. I didn't do brilliantly but I finished my studies, got my head down with the cricket, and got myself back on track.

What are some of your fondest memories of playing together?

K: The first time we played together for Ireland would be a massive one. It was in the European Championships in 2006, against Italy or Denmark I think. It was a nice moment for Mum and Dad to see us playing for our country together and it just highlighted how much we had put in. Every day of the week we used to go out after school, put up a pad in front of the wall, grab a tennis ball and bat, and play a "Test match". And here we were, playing for our country.

N: Kev had made his Ireland debut in 2006 against England at Stormont but Kent wouldn't release me and I was playing in Stockton-on-Tees against Durham, which was a nightmare really. I remember sitting in the bar with my pads on watching the Ireland match and Durham fans shouting that there'd been a wicket and I had to go out to bat. Four runs later I was back in the bar and watching the match!

K: Back then there wasn't a mandatory release for international games. Thank god that's changed in the last couple of years.

The victory over England in the 2011 World Cup must be right up there. Niall, did you know Kevin had an innings like that [113 off 62 balls - the fastest ton in World Cup history] in him?

N: He played a similar innings against Kenya in 2007, when he got 142. People don't Kev enough credit for his shot selection - he's got huge hits in him but he doesn't just swing at every ball like an Afridi. So I knew he had the capability, it was just amazing that it happened on such a big occasion. I remember I got out for 29 - a horrific slog-sweep off Swanny - and I was sitting with Joycey, who'd just been out stumped, in the dressing room cursing our luck. We sat inside for half-an-hour and kept hearing people shout "Shot!" and then all of a sudden Kev had 30, then he had 40, 50… Some of the shots he was playing, putting Jimmy Anderson 20 rows back… and then Anderson and Prior trying to sledge him and Kev giving it back twice as good! It was just unbelievable. The type of innings you probably won't ever see again.

K: The great thing for me was to be able to do it on the biggest stage, as Nialler had done in 2007 against Pakistan. I've never lacked self-confidence, I've never felt that I wasn't good enough to play international cricket, and I was very blessed to be able to work with some of the best coaches in the world between 2007 and 2011, like Gary Kirsten and Eric Simons. It was a great opportunity to learn and expand my game so as much as that innings was about talent and little bit of luck, it was really down to a lot of hard work. Thankfully it paid off.

Niall and Kevin O'Brien as kids riding a horse Camilla O’Brien

Kevin, that innings led to you becoming a poster-boy for Irish cricket. Is that something you were comfortable with?

K: I wouldn't say poster-boy - they're usually quite attractive! I'm probably not as comfortable in the limelight as Nialler but I'll certainly take all the advantages that come with it. I suppose if you score a hundred in front of a million people then you've got to expect some kind of publicity to come your way.

It acted as a springboard to represent Twenty20 franchises across the world but is there any frustration that you haven't played more first-class cricket?

K: It's not really my priority. I do like four-day cricket whenever I've played it for Ireland but it's not my favourite format and to be honest with you I probably wouldn't last a season in county cricket. It's a hard slog on the body being an allrounder and the type of player that I am, whether it's the first ball or 100th over of the game I'm still going to be giving 100%. I suppose it's unfortunate that in my own mind I wasn't up to first-class cricket but I thoroughly enjoy white-ball cricket and I want to play as much of that as I can. If I can play Test cricket on top of that in the years to come then I'll cherish those games as well.

Do you think you'll get a chance to walk out together in a Test match for Ireland?

K: Well it depends on when Nialler hangs up his boots!

N: I can't see it in my time. I'm 32 and I hope to play for four or five more years. Warren Deutrom [Cricket Ireland chief executive] has set out a vision for Test match cricket by 2020 and I think I'll be in the stands by then, telling everyone how many runs I'd have scored if I was playing. You're always a better player when you retire!

K: The more performances we put in at World Cups and qualifying tournaments, the more ammunition we give Warren Deutrom to go and speak to the ICC and say, "Listen, we're ready". From the current generation's point of view, hopefully that's going to be in the next couple of years. It would be a shame if none of the current team got to pull on a Test match jersey for Ireland.