Irish heart beats for London boy O'Brien after 'horror show'
He earns his wages with a club nicknamed the Lions.
But when the national team who wear three lions on the shirt came calling, the question of dual nationality, or assessing the options, did not even enter the head of Millwall striker Aiden O'Brien.
Irish Blood, English Heart suggests itself as a theme tune for the 23-year-old Londoner, who is in the senior Ireland squad to face Moldova and Wales in two vital World Cup qualifiers.
The forward almost lost his place in the squad before it was named as he fluffed his lines at an audition only last week, when Martin O'Neill went to the New Den to watch O'Brien play against Reading.
"I had a horror show, I didn't play well," O'Brien says of that game only seven days ago.
"I won't blame it on anything, I always turn it back on myself, I just didn't turn up for that game. That one game where he comes along, I didn't have my game. I haven't had a chance to explain that to him, hopefully I have shown him on the pitch that it was just a little hiccup."
He has had to be patient in his bid to wear the green as his last involvement with the international set-up was three-and-a-half years ago, when he won his 10th and final U21 cap, so long ago that a couple of team-mates that day are no longer in senior football.
O'Brien is the kind of player who suffers from the absence of B internationals on the Irish football calendar (the last one was in 2008) to keep a link with the national side once a player is over age for the U21s.
But, on the back of good form with his club in the Championship, here he is, in the senior squad, the lure of a senior cap proof that O'Brien first joined the Ireland set-up at the age of 16, having been spotted by Mark O'Toole, the vastly under-rated but hugely important Irish scout in England.
"I got approached when I was younger by England and Ireland and there was no decision," says O'Brien.
"I didn't get approached personally, they approached my dad. And my dad was like 'there's no chance'. I was like 'no, don't be silly, green all the way'.
"And I've made it this far, I've got to this stage, I don't want to end, I want to keep going and hopefully I can make a big name for myself with this country because that's what I want to do.
"You're playing for the country, it's not a club, this is a whole country backing you and you want to make that badge, that country, proud. You want to play proudly with that crest on your shirt and that's all I want to do.
"I want to play with a smile on my face for this country and hopefully I can get far," added O'Brien, who qualifies through his maternal grandparents Teresa (Dublin) and Patrick (Tipperary).
"My mum's mum and dad were fully born and bred Irish and moved over. My dad's side is fully English so I've never fully been brought up in Ireland, as you can tell. The inside, the core, is Irish."
O'Brien is behind fellow rookies Scott Hogan and Sean Maguire in terms of experience and exposure but he says he can play a role is asked.
"Whatever team and subs Martin O'Neill picks on the day that will be the team he thinks will win. We've just got to train every day, give it 100 per cent and hopefully get the win over Moldova," he added.