Ulster prop Tom Court will join London Irish in the summer on a three-year deal.
The loosehead has won 32 caps for Ireland, and he was called up by the British & Irish Lions for last summer's tour of Australia, the country of Court's birth.
He grew up in Australia and was National University shot put champion there for three years, and only started playing rugby in 2004.
He moved to Ulster in 2006, and played for the Ireland A side before he had made his first appearance for his new province.
London Irish Director of Rugby Brian Smith told the club's: "Tom is a current Irish Test player and British & Irish Lion. He's a terrific signing for the club as we look to add steel to the pack.
"With David Paice and Halani Aulika extending their contracts it means we'll be able to field an all International class front row next season."
Court said: "I have enjoyed eight fantastic seasons at Ulster and will leave the club with many happy memories. London Irish is a new challenge and one I am looking forward to.
"There is still a lot of work to do for the remainder of this season at Ulster and that will be my immediate focus."