Brian O’Driscoll believes Sean O’Brien’s Ireland career will come to a shuddering halt after the the World Cup in Japan.

The 32-year-old's move to London Irish was confirmed on Monday afternoon, after initially hitting the headlines before the weekend.

Leinster provided a glowing reference for the departing Carlow native.

The province admits while they are gutted to see him go, there was nothing they could've done to prevent the imminent exit.

The Ireland international has agreed a three-year contract worth a reported €500,000 a year.

Senior coach Stuart Lancaster conceded to the Irish Mirror it was almost out of Leinster's hands as soon as a central contract wasn't offered by the IRFU.

"When you lose a player of Sean's quality, everyone's disappointed," said Lancaster. "In an ideal world, you keep all your best players until the very end.

"It was almost out of Leinster's hands as soon as that national contract wasn't offered and Seanie got such a fantastic offer.

The curtain will likely come down on the Tullow Tank’s career after the Rugby World Cup.

His former team mate Brian O'Driscoll doesn't think the IRFU will deviate from their policy that excludes overseas players from selection.

Simon Zebo was ruthlessly cleaved from the squad when he moved to Racing 92, Donnacha Ryan’s career also came to an unceremonious end after his departure from Munster.

Sexton was the exception to the rule, his foray to France never harmed his hopes of lining out for Ireland.

The Tullow Tank is rolling in to Reading

O’Driscoll understands why the IRFU decided not to strictly enforce their edict when it comes to the out-half, but doesn’t expect O’Brien to receive the same treatment:

“It’s a tough one, it depends on what Andy Farrell is told or what his policy is and whether he continues with the Schmidt and Nucifora regime or not.

“The reality is though we’ve got very few scenarios similar to the Johnny Sexton case where he was far and away the best option.

“Whereas Sean O’Brien even at the peak of his powers Sean O’Brien of two years ago.

“Yes he’s definitely better than the other two sevens [Dan Leavy and Josh van der Flier] including Jordi Murphy as well, but they’re not a million miles behind.

“Whereas Sexton to the next player it was quite the gulf with respect to those other players, such was Johnny’s quality.

“We’re unlikely to find ourselves in that predicament again, I think players know if they go overseas its highly likely that they’re not going to be selected nationally.”