Chris Ashton will join Saracens next season after being attracted by the opportunity of working with his former Wigan rugby league idol Andy Farrell.
Ashton, who made his successful cross-code switch from Wigan to Northampton in 2007, met with Farrell, the Saracens head coach, before signing his long-term deal with the Aviva Premiership champions.
But the 24-year-old's move from Franklin's Gardens is not without controversy.
Ashton had decided on his return from the World Cup that he wanted to explore his options and it is understood he never entered negotiations with Northampton.
The England wing has insisted he remains committed to the Saints - but at this stage it is uncertain whether he will play for the club again.
Ashton has been dropped for Northampton's Heineken Cup clash with Munster on Saturday, amid rumours of a training ground row with director of rugby Jim Mallinder.
"We're obviously disappointed that Chris has decided he wants to play his rugby elsewhere," Mallinder said in a statement.
"We have known for some time that Chris was looking elsewhere and had been planning to use that part of the salary cap by strengthening our squad in a number of positions.
"We've also got several good wingers at the club who have all been pushing for a first team spot this season, the likes of Jamie Elliott, Vasily Artemyev, Scott Armstrong, Paul Diggin and Noah Cato, plus Anders Mogensen in the academy who has been playing well on loan for Cambridge.
"They are all part of our plans going forward and will all contribute massively to the continued development of the Saints."
Ashton has scored a remarkable 90 tries for Northampton in 106 appearances since his move to Franklin's Gardens and he has built a reputation for being one of the game's deadliest finishers.
At Test level, Ashton has touched down 15 times in just 18 appearances for England, including four tries against Italy at Twickenham during last season's Six Nations title campaign.
Ashton found himself at the centre of controversies off and on the field during 2011 and he has been criticised for chasing the money by moving to Saracens.
Mallinder said last month that Northampton would not stand in the way of a player who had a "massive financial offer" on the table.
Those close to Ashton insist otherwise, arguing that had money been the motive for his move then Northampton would have been engaged in talks in a bid to drive up his salary.
"Chris felt he wanted to explore his options and this will be a new experience," said a source.
"Chris is a Wigan lad at heart. Andy Farrell is a legend in Wigan and Chris has always looked up to people like him. That influenced his decision.
"Saracens are champions and they are becoming a force in Europe."
Ashton will get a chance to work with Farrell while on England duty from next week, with the Saracens head coach part of Stuart Lancaster's interim management team for the Six Nations.
Northampton meet Saracens at Vicarage Road on March 4, when Ashton will be with England, but the two clubs could lock horns in the end-of-season play-offs.
"I've decided to join Saracens from next season... until then it's all about Saints," Ashton insisted on Twitter.
His arrival at Saracens next season will strengthen an already powerful back division that contains fellow England squad members David Strettle, Brad Barritt, Owen Farrell, Alex Goode and Charlie Hodgson.