League Two clubs have not missed out amid the flurry of managerial sackings recently with Simpson leaving Edgeley Park after less than six months in charge.
The former Preston and Shrewsbury boss must have been looking over his shoulder after a run of three wins from nineteen games left the Hatters in 21st place in the division.
Northampton eased past Stockport when the two sides met at Sixfields in early December, goals from Thornton and Jacobs sealing the three points.