Sam signed a permanent basis in January 2016 after a loan spell with Valley for the first part of the season.
The young left back, who was a first year pro with Northampton, originally joined Valley on a youth loan along with fellow Cobblers youth product Danny Clifton in August 2015 under Gary Mills.
Warburton, who has featured at left back and on the left of midfield, was released by Northampton at the end of his contract when he made his move to Rugby permanent.
Sam left the club in February to join Vanarama North side Nuneaton Town FC. |
