The 21-year-old Londoner's new deal keeps him at the club until 2010.

"He's still got some improvements to make and we feel that we have got the right environment here for him to do that," said coach Brian McDermott.

He added: "We are showing faith in our local and British youngsters and we are more than happy that Louie has put his faith in us as well."

McCarthy-Scarsbrook said: "It's great to know I have my future for the next three years secured and to be in that situation with the Quins is fantastic.

"London is my home, there is nowhere else I would want to be playing top level rugby league."