Although his favoured position is as an open side flanker, Clark is comfortable in all three back row positions and his signing continues the Saints’ policy of flexibility in a crucial part of the team.

Clark made 23 appearances during his maiden season at Leeds, 17 of those as a member of the starting line-up. A graduate of the Leeds Academy system, Clark’s abilities and potential were recognised by two consecutive Young Player of the Year awards and a call-up for the England Under-20 squad in 2008.

After helping the squad reach the 2008 IRB Junior World Championship (JWC) final, he was back in the side for 2009, this time as captain for both the Six Nations and the JWC campaign in Japan, when England once again made the final.

So far this season he has missed just two of Leeds’ matches in the Guinness Premiership, LV= Cup and Amlin Challenge Cup, but he knows that he will have to work hard for a place in the Saints line-up.

“It’s going to be a real fight for me to get into the squad,” Clark said. “I’m under no illusions about that, and I’ll have to get my head down and graft and then make the most of my opportunities if I get them. There are some quality players at Northampton and hopefully being around them will improve my own game.

“The Saints is a club with ambition and a philosophy of having young, English players in their team. They do the basics very well and match this with flair and talent. It will be great to play with the young talent and the experienced guys as well. There is a great set-up there and the opportunity to develop myself and progress is what excites me.

“I also know how passionate the fans are from playing there and I’m looking forward to joining the club.”

Clark also acknowledged that it had not been an easy decision to leave Leeds, where he has been a player since he was 14.

“It was a really hard decision to make and my leaving isn’t a negative reflection on Leeds as a club,” he said. “I’ve grown up there and it will always be close to my heart. But I’ve made a decision to push on and make the best of myself, and Northampton was an impossible club to say ‘No’ to.

“However I am fully committed to Leeds until the end of the season and am desperate to go out on a high.”

“Calum has made an excellent start to his career and we are excited that he will be part of our squad next season,” said director of rugby Jim Mallinder. “He is rightly regarded as one of the brightest prospects in the country. He has good ball handling skills, physicality and a mature approach to the game that was recognised when he was made England Under-20s captain last year.

“We understand that there was a lot of interest from other clubs and am delighted that Calum has confidence in where we are taking the club.”