The 28-year-old hooker has been a regular for the Irish province since making his debut against Toulouse in the Heineken Cup in October 2000.

An aggressive scrummager, Shields won two caps for Ireland in 2003 and he recently won his 100th Ulster cap in the Magners League victory over the Dragons.

As well as collecting a Celtic League winners’ medal last season, in 2004 Shields won the Celtic Cup with Ulster and the All-Ireland League with his club Ballymena.

He brings plenty of leadership experience to Franklin’s Gardens. Educated at Belfast’s premier rugby school, RBAI, Shields captained the Irish Development team in 2003, Ulster U20 in 1998 and Ulster Schools in 1997.

Paul Shields in action for Ulster

“It was an easy decision to make,” said Shields. “Northampton has a lot of history and is one of the biggest clubs in England. I remember watching Buck Shelford and Martin Bayfield play for the Saints when I was growing up and the club has a high profile in Ireland.

“It’s not unusual to see kids walk around with Northampton Saints shirts on.

“I’ve played here with Ireland ‘A’ and visited with Ulster so I knew that the facilities are world class. There’s everything here for players to push on and improve.

“Northampton have also been fantastic and professional in my dealings with them, looking after both myself and my fiancée Gemma.

“And whenever I met Paul Grayson, Peter Sloane and Frank Ponissi their ideas and ambitions were what I wanted to be a part of to put the Saints back at the top of the GUINNESS PREMIERSHP.”

Saints head coach Paul Grayson said: “Paul has a track record of quality, especially in his last few seasons as part of the successful squad at Ulster.

“He will be a useful addition to the squad and will challenge and help develop the likes of Dylan Hartley.”