GEORGE FRIEND admits the lure of teaming up with Aitor Karanka again was a key factor in his decision to leave Middlesbrough in order to join Birmingham City.

Friend was confirmed as Karanka’s first signing as Birmingham boss over the weekend, with the full-back having signed a two-year deal at St Andrew’s.

His decision to join the Blues ends an eight-year stay on Teesside, with Friend having become a firm fans’ favourite after costing just £100,000 when he joined from Doncaster Rovers in 2012.

The 32-year-old was offered a new deal under Neil Warnock, but Boro are understood to have been pushing for a 12-month contract on significantly reduced terms to Friend’s previous deal.

Birmingham’s willingness to agree to a two-year deal offers the defender greater long-term security, and means he is able to renew his relationship with Karanka, who was his manager at Middlesbrough when he won promotion to the Premier League.

“Aitor is a big reason (for the move),” said Friend, who made a total of 299 senior appearances for Boro. “I had a successful time with him at Middlesbrough, and I know what he’s all about. I know that he’s looking to build something here, and the club has got ambition in that aspect.

“There’s a good feel around the place with his appointment. He was keen to bring me in, and I’m looking forward to getting going. I’m not sure I’ve been a first signing before at a club, but I guess I’ll take that honour.”

Friend played the best football of his career under Karanka, with his performances in the promotion-winning season of 2015-16 playing a key role in Boro’s successful elevation to the top-flight.

He was arguably the best defender in the Championship that season, and he remained an influential figure at both left-back and centre-half after Karanka’s departure.

However, his performances on the pitch were only part of the reason why he became such a popular figure. Off the field, Friend embraced life on Teesside and became a passionate supporter and advocate of his adopted home.

He wore the captain’s armband with distinction and championed a wide range of charitable causes as well as acting as the figurehead for Middlesbrough’s own charitable foundation. He was the driving force behind the charity calendar that helped raise funds for the steelworkers affected by the closure of the SSI plant, and continued to work with a number of social projects and initiatives long after the works were closed.

When he was pictured contemplating his future in the dug-out at an otherwise deserted Riverside after the final home game of the season, the likelihood of him moving on prompted an outpouring of praise and positive comments on social media, and Boro fans were quick to pay tribute after his departure was finally confirmed at the weekend.

“It’s important to stress that it wasn’t a decision I took lightly because I’d built a lot at Middlesbrough and having been there for so long, had a good connection with the club,” said Friend.

“I had a really successful time there and loved it. What I would say is that I'll bring that same drive, passion and commitment now I'm at Birmingham. I'm really excited to get going and hopefully the fans will see that as well.”

Friend’s departure leaves a hole that Warnock will be desperate to fill as quickly as possible, but while Marvin Johnson’s decision to sign a new deal last week was welcome, Grant Hall remains the only new player to have arrived at the Riverside since the end of last season.

Having missed out on Kieffer Moore, who joined Cardiff City last week, Warnock has been back in touch with the administrators running Wigan Athletic to discuss a move for the Latics’ £2.5m-rated midfielder Joe Williams.