Chris Wilder tied up a deal for the midfielder on Thursday while allowing John Joe O'Toole to join the Cobblers' weekend opponents.
Granted permission to play against his parent club, O'Toole was handed his Shrimpers debut by boss Phil Brown.
Ivan Toney, meanwhile, was included on the substitute's bench.
The 18-year-old striker underwent a medical at Wolverhampton Wanderers earlier in the week with a view to a move to Molineux that would have broken the Cobblers club record but the deal fell through for reasons that have been speculated at but not confirmed.