Ryan Watson scored two in two minutes to continue his sensational form while Fraser Horsfall's close-range header and a fourth by Sam Hoskins - or Ryan Edmondson - put the gloss on a highly impressive victory. Here are our player ratings from the PTS....
1. Jonathan Mitchell
Would have had another clean sheet but for a soft late penalty, although he was unlucky not to keep it out. Pompey didn't properly test Town's goalkeeper outside of that, only forcing him into a couple of very comfortable saves.. 7.5
2. Peter Kioso
Some lovely play with Hoskins down the right won the corner which led to Town's second goal. Wasn't the only time those two combined. Not a tall man but he's good in the air as he showed when Pompey launched balls into the box... 8
3. Fraser Horsfall
Backed up his outstanding performance in midweek with another very strong 90 minutes here, including scoring his second goal for the club. Tracked runners and won his defensive headers. Unlucky to give away a harsh penalty... 8.5
4. Lloyd Jones
Continues to be a revelation for the Cobblers since joining two months ago. Won everything that came his way, either aerially or on the ground, and is a very composed figure at the centre of defence. Even finished the game as captain... 9