Newcastle have completed the signing of promising young Swindon defender Ben Tozer.The 17-year-old has been in negotiations with the Magpies since the end of December but both parties have now agreed an undisclosed fee and a four-and-a-half-year deal. Tozer joined the Robins from Plymouth in the summer and was handed his senior debut in the club's Carling Cup tie against Charlton in August. He has since gone on to make seven first-team appearances for Swindon but will move to St James' Park with immediate effect. Magpies boss Sam Allardyce is now expected to loan him out to gain more first-team experience. Tozer told Newcastle's official website: 'I was called into the manager's office (at Swindon) three or four weeks ago and he said that the club had accepted an offer from Newcastle. 'I could not believe it and straight away I said that I could not turn the offer down. 'It's a brilliant feeling, it really is a dream come true and it hasn't quite sunk in yet. 'Newcastle is a massive club with great fans, it's a lovely place with nice people and I can't wait to get started. 'I have spoken with Sam Allardyce - he's great manager and I'm looking forward to working with him. 'It's been a brilliant experience at Swindon and I thank them for what they have done for me, but I'm looking forward to the future.'