Legendary Arsenal manager Arsene Wenger has admitted his mistake in letting Matthew Upson leave the club in 2003. Wenger has consistently revealed in the past that the decision was one of his worst as the Gunners boss. Matthew Upson became an Arsenal player in 1997 when the North Londoners paid £2m to sign him. Matthew Upson was signed from Luton Town shortly after he made his professional debut at the club. Upson didn’t really settle at the club as he was farmed out on loan three times. The 41-year-old went to Nottingham Forest in 2000 and that loan spell