Darren Pratley's close-range finish was followed by an own goal by Jack Sowerby just five minutes later. Here are our player ratings...
1. Jonathan Mitchell
His main contribution was to pick the ball out of his net. Couldn't get close to either goal and didn't have a single other save to make... 6 Photo: Pete Norton
2. Luka Racic
Harshly booked for a clean early tackle but did well not to fall into Charlton's trap and avoid being sent off. His sliced clearance under no pressure out for a corner, instead of a throw, resulted in Pratley smashing home... 5.5 Photo: Pete Norton
3. Cian Bolger
Followed Tuesday's excellent display with another decent outing here, especially in the first 45. Didn't allow Addicks frontman Bogle a sniff of goal... 7 CHRON STAR MAN Photo: Pete Norton
4. Fraser Horsfall
Those two goals in five second-half minutes will hugely frustrate Cobblers because otherwise the defence - and Horsfall in particular - were completely untroubled... 7 Photo: Pete Norton