Sean O'Brien hopes he can extend his Ireland career beyond the World Cup despite trading Leinster for London Irish after the autumn's global battle in Japan.

British and Irish Lions flanker O'Brien admitted he has been driven to tears by his decision to leave Leinster after the 2019 World Cup, to join his first Ireland boss Declan Kidney at the Exiles.

The 32-year-old knows he risks falling foul of the Irish Rugby Football Union's (IRFU) policy of only selecting overseas-based players in extreme circumstances.

Johnny Sexton remains Ireland's sole overseas star to continue to win selection - during his stint with Racing 92 - but despite the likes of France-based Simon Zebo and Donnacha Ryan currently being overlooked, O'Brien is refusing to give up on his Test career.

"If I'm fit and well I think I can add value to this group: even after I leave Leinster I'd hope to be selected," said O'Brien.

"But that's so long away and it's probably a decision that the coaches and whoever is in charge at the time will have to make.

"But there's always hope there, I think, that regardless of where you are you're still in with a shout if you're playing well enough.

"Until the World Cup finishes that is all up in the air.

"Afterwards I would hope to still be in the mix if possible and if fit, but I haven't really thought that far ahead yet.

"Because I am contracted to the World Cup it is what it is at the minute. But you never know what will happen about it.

"There's been a few tears shed over the last few months thinking about all of this.

"When you do make your final decision, it's a tough place, at the end of it all you're just packing your bags and you're walking out the door and moving to a different club.

"It hasn't been that easy but it is what it is; you back yourself to go over there and do a job.

"It was probably the toughest thing I ever had to do, was to move away from Leinster. I never thought I was going to be in that situation but that's the way it goes sometimes and that's professional sport.

"I hadn't thought too much about it, it all happened very fast.

"I know at the end of my contract that I will have done what I could for Leinster, to the best of my ability in those 10, 12 years. That sits well with me. It's not going to be a case of me leaving with a load of regrets."

Defence specialist Andy Farrell will replace Joe Schmidt as head coach after the World Cup, but O'Brien insists he has not sought any assurances with the former dual-code England international over his future.

"No I haven't spoken to Faz about it, it's too far away to think about really," said O'Brien.

"I am only back in a couple of weeks here so it's not a priority for me at the minute.

"I want to focus on playing well back here and staying fit and I'll think about that stuff in November and December."

O'Brien's impending departure has been eased in a fashion by Robbie Henshaw signing a three-year Ireland and Leinster contract extension.

"Robbie has established himself as a leader within this Ireland squad and has delivered consistent world-class performances which have helped to drive the sustained success enjoyed by the national team," said IRFU performance director David Nucifora.

"He has a hunger for improvement and in driving the standards of those around him."