Ex-England flanker Courtney Lawes will leave Northampton Saints at the end of the season to join French club Brive.

Lawes said Northampton did "everything they could" for him to stay, but the offer from second-tier Brive was "transformative" to him and his family.

Saints director of rugby Phil Dowson said it was "impossible " to sum up Lawes' contribution to the club.

Lawes, who retired from international rugby with 105 caps after the World Cup in France, is the second recent high-profile departure from the Premiership leaders for next season after England flanker Lewis Ludlam, who has been linked with a move to French club Toulon.

"I want to make it clear that I really would have liked to end my career as a one-club man, and Saints did absolutely everything they possibly could to make that happen - our conversations were all very positive," said Lawes.

"But, first and foremost, I have to make sure that my family and I are in the best position possible for my retirement, which will be in the next couple of years.

"This is likely to be the last contract I'll ever sign, and the offer I have received to play overseas will be transformational for my family, so there was no way I could turn it down and I took the decision to move away from Northampton."

Lawes said he was "so grateful" for everything Saints had given him and said the supporters had been "amazing".

"I've been through it all with Saints and I just hope that my efforts on the pitch have reflected my appreciation for the club," he said.

"It's obviously incredibly sad for me to be leaving, but ultimately I know I am leaving Saints in really good hands on and off the pitch with the players, coaches and staff we have."

Lawes 'still one of the very best'

Lawes helped Saints win promotion back to the Premiership from National One in his debut season in 2007 and went on to win the European Challenge Cup in 2009, the Anglo-Welsh Cup in 2010 and the European Champions Cup a year later.

He also was a Premiership title winner in 2014 - the same year Saints won the Challenge Cup again.

"He's still one of the very best - if not the best - number sixes in the world," Dowson said.

"He's done it all in a Northampton shirt, his international experience is almost unparalleled, and off the field he gives our group so much in terms of confidence and leadership.

"I am convinced he would have loved to stay here at Saints to finish his career, but sometimes the offer is simply too good to refuse, and he's absolutely earned the right to accept it. He's got a young family and I'm sure this new adventure will be a great experience for them too.

"It speaks volumes about Courtney's talent and mindset that he didn't feel like he got the best out of himself last season in a Saints shirt because of injuries, so he decided to stay on for another year and finish his time in Northampton on his own terms."