Cheered on by 1,494 fans in the South Stand, Knight topped off a superb first half showing for Town with a couple of goals out of the top drawer.
Knight's 16th goal arrived on 27 minutes when he patiently waited on the edge of the area until Danny Schofield sprang the offside trap and laid the ball on for Knight who couldn't miss after seeing an opportunity literally open up in front of him.
John Thorrington's through ball set Knight on the run for his second just 5 minutes later.
The on-loan striker took up the ball neat the half way line and galloped upfield without much interference from any Northampton defenders until he reached the area and cleverly drew Keith Welch off his line before planting the ball into the back of his net to make it 17 for the season after exactly 5 months.
There seemed to be plenty of space in which to play as the generous Cobblers defence allowed Schofield and Thorrington the room to run and create.
Knight could have had more goals during the intense first half but he might also have provided one had his centre across the face of goal been turned in by a Town player at the end of the first period.
Northampton's defence was in total disarray for much of the first half and, despite Jamie Forrester posing some questions to the Town defence, there was little to worry Margetson with Gray and Jenkins imperiously holding the defence together at the back.
Jenkins and his defensive cohorts were comfortable with what little threat Northampton presented and even the introduction of Derek Asamoah and Marco Gabbiadini seemed to make little difference to the Cobblers' fortunes.
Andy Booth came on in the second half after chanting from the South Stand and, although Kenny Irons went close with a deflected shot, the Terriers looked relaxed as they cruised to victory despite an uninspired second half.
Read Mel Booth's report in the Examiner on Monday. Have your say on this match in the message board below. Selected messages will be published in the Examiner.
Town (4-4-2): Margetson, Jenkins, G Evans, Clarke, Gray, Thorrington (Booth 73), Schofield (Heary 86), Irons, Holland, Knight, Facey (Hay 90)
Subs not used: Moses, P Evans
Scorer: Knight 27, 32
Northampton (4-4-2): Welch, Frain, Sampson, McGregor (Gabbiadini 57), Hunt, Parkin, Hunter, Burgess, Forrester (Asamoah 57), Hargreaves, Marsh (Hope 80)
Subs not used: Sollitt, Carruthers
Referee: R. J. Olivier (Sutton Coldfield)
Attendance: 10,783 (790 Away Fans - 1,494 Town fans in South Stand)
Match points follow on subsequent pages.
88 mins: Thomas Heary had come on for Danny Schofield but Town were not making as many inroads as they had done in the first half.
80 mins: Schofield won a corner after Hunter thwarted his goalside efforts with support from Knight.
76 mins: The game seemed to have ended at half time as both clubs found chances few and far between in a tedious passage of play.
72 mins: Andy Booth was reintroduced for John Thorrington.
68 mins: Holland's right footed effort went wide.
65 mins: Thorrington slipped between two defenders and had options in Knight and Facey but chose to go for goal but his effort was poor.
59 mins: Irons hit a great shot which drifted wide.
58 mins: Asamoah and Gabbiandini replaced Forrester and McGregor as the Cobblers went for goals.
57 mins: Knight's clip fell between Facey and Thorrington. The American evaded a tackle from Frain.
55 mins: Town were taking it easy as chances became few and far between.
50 mins: Jenkins' cross was overhit for Facey as Town came out well in the opening exchanges of the second half.
Leon Knight was the star of the show once again as Town ripped the Cobblers to shreds in an exciting first half.
The young striker, on loan from Chelsea, scored his 16th and 17th goals of the season taking advantage of some lackadaisical defending by Northampton which left their 'keeper isolated.
Danny Schofield sprang the offside trap for Knight's first and John Thorrington provided an easy through ball which saw Knight run 40 yards through an ineffective Cobblers defence to score his second.
The Cobblers offered little in the way of a reply, with Jenkins and Gray solid at the back, and a vocal McAlpine crowd got right behind their side.
45 mins: Facey found Knight who clipped the ball across the face of goal but Danny Schofield arrived too late to knock it in.
44 mins: Nathan Clarke headed the corner just wide.
43 mins: Schofield squared for Irons who hit a shot which deflected behind for a corner.
36 mins: Forrester netted but Margetson looked at the linesman who had flagged offside.
35 mins: Facey was offside as Town easily ripped their way through the space between the central defenders.
34 mins: The South Stand was thronging with singing Town fans who rejoiced following the second Town goal.
32 mins: Knight was free again after he latched onto a through ball from Thorrington 40 yards out and raced into a scoring position before slotting home with aplomb past the hapless Keith Welch!
27 mins: Leon Knight hammered another goal for Town after Danny Schofield put him through. The little striker beat the offside trap and couldn't miss.
19 mins: Town won a free kick 30 yards out but Irons could only hit the wall in this tight contest.
15 mins: A header at the far post from a corner was palmed away by Margetson but almost fell kindly for Parkin.
10 mins: McGregor's shot almost caught Margetson napping but he watched it sail wide of his left hand post.
9 mins: Schofield miscontrolled after a good pass. The McAlpine pitch looked firm and the bounce was deceiving.
6 mins: Town were comfortable on the ball, with much of the possession as they enjoyed an easy start against Northampton.
5 mins: Forrester beat Clarke and crossed for John Frain but Martyn Margetson collected with Gray bewildered.
3 mins: There was plenty of space for Leon Knight to exploit as the Cobblers played deep.
1 min: Thorrington's run and cross fell nicely for Facey but his shot was repelled by Burgess.
Andy Booth returned to the bench after the departure of Clyde Wijnhard as Town's first XI remained unchanged for the 5th game in a row. Paul Evans, Town's new goalkeeper signing, replaced Phil Senior on the bench.