George McCartney has become the most expensive player in Northern Ireland football history.
Two years after leaving Sunderland for West Ham United the 27-year-old has returned to the Stadium of Light in a £6million package.
The fee paid by Black Cats’ boss Roy Keane outweighs the sum that Celtic paid for Neil Lennon over seven years ago by £250,000 as Sunderland continue to splash the cash.
McCartney is looking forward to a bright future with Sunderland - who he believes have made great strides since he left to join West Ham.
Signing a five year deal, McCartney is Keane's 10th signing of the summer, joining the likes of Djibril Cisse, El-Hadji Diouf, and Northern Ireland team-mate David Healy.
McCartney will also link up with former Hammers team-mate Anton Ferdinand, who moved to Wearside last week.
McCartney told the club's official website, www.safc.com: "It's a great move for me and great to be back at Sunderland.
"The club has moved on over the last two years and I think there are exciting times ahead.
"The fans were always good to me and I hope that will continue and that we can have a good season.
"The club has changed a lot since I left but there are still a few familiar faces around, I can't wait to get going."
McCartney came through the academy at Sunderland and made his senior debut in a 3-0 League Cup win against Luton in September 2000.
He made 157 appearances for the Black Cats before moving to West Ham two summers ago.
The Belfast man was an ever-present for the east Londoners last season and he signed a new five-year deal earlier this year.
The club rejected Sunderland's initial approach earlier in the summer but the player handed in a written transfer request.
McCartney, though, revealed on the Hammers website his return north was for family reasons as his wife had not settled in the capital.
He explained: “I had two great seasons with West Ham and I'd like to thank them for giving me the opportunity to play for a club with the history they have and their fantastic supporters. But for personal reasons alone, this move is right for me."
Keane said of McCartney's return: "It's great to be able to bring George back to Sunderland.
"I've made no secret of the positions I've been looking to strengthen and a left-back was one of my priorities, I'm delighted.
"George's experience will prove invaluable and he shouldn't take long to settle in as he knows a lot of the lads already and obviously he knows the club inside out.”