Andy Kirk's eighth league goal of the season handed the Cobblers a half-time lead with a well-taken strike.

But Damian Spencer rose highest to head home Alan Wright's cross and draw the Robins level just after the interval.

However, substitute Gilligan was on hand to drill home the winner for the hosts from 25 yards and extend their impressive form at Sixfields.

Northampton: Bunn, Crowe, Hughes, Dolman, Jones (Jackman 71), Larkin, Russell (Burnell 83), Bradley Johnson, Holt, Hubertz (Gilligan 71), Kirk

Subs Not Used: Dunn, Doig

Goals: Kirk 22, Gilligan 80

Cheltenham: Higgs, Gallinagh, Duff, Townsend, Wright, Sinclair, Finnigan, Bird (Reid 85), Myrie-Williams (Vincent 72), Connor, Spencer (Lindegaard 78)

Subs Not Used: Scott P Brown, Caines

Booked: Finnigan

Goals: Spencer 50

Att: 5,012