Saints centre Mark Percival has signed a deal to stay at the club for another four years.
The 22-year-old centre has committed his future to the club by signing an extension until the end of season 2021.
He had been one of a number of young English players attracting attention from Australian NRL clubs.
Saints chairman Eamonn McManus said: “It’s great news for the Saints and for the game that Mark Percival has committed to a new long term contract with us.
“He’s one of our many home-grown academy products and is a testament to the youth policy in which we have invested so much over the years and which continues to produce top class talent.
“Mark is already international class, is still in the early stage of his career, and will only improve further. This is a huge and timely boost for all at the club.”
Percy made his debut against Leeds in the 2013 season and has since gone on to score 420 points in 79 games.
He came to the club via Halton Hornets and, after impressing in the Academy, has become an integral part of the first team squad, as well as receiving international recognition for England.
He also made three appearances for the national team in the 2016 Four Nations.
Percival added: “I love this club. I have been here since I was 12-years-old and I want to help it win more trophies. That is my aim.
“I’m happy here. I love playing and love the friends I have at this club and the team around me. I just want to improve and get better and I’m looking forward to doing that over the next four years.
“It was a dream to play for England but my priority is to do well for this club. If I do that then I give myself the best chance of playing for England again.
“I’d like to thank everyone at the club for their support and belief. Without that I wouldn’t get the chance to do what I do and I want to give it back to them on the field.”