McGeehan scored shortly before the half-hour mark and then again with six minutes to go on a wonderful Sixfields night. Here are our player ratings...
1. Nik Tzanev
Solid and secure when called upon, which wasn't all that often. Strong hands to beat away Collins' strike and then at full stretch when denying Mothersille. Should do his confidence the world of good... 7.5 Photo: Pete Norton
2. Aaron McGowan
Thrived on the intensity of derby day. The aggressive nature of Town's out of possession approach meant there were always going to be hairy moments at the back and he needed to make some last-ditch interventions... 7.5 Photo: Pete Norton
3. Jon Guthrie
He's the rock that holds it all together. So incredibly reliable and his team really needed him here. Made at least three vital and superb interventions - two tackles and one block - when Posh looked certain to score. Cobblers lose this game comfortably without him in the side... 9 CHRON STAR MAN Photo: Pete Norton
4. Nesta Guinness-Walker
His shaky start was understandable given his unfamiliarity at centre-back. Loose early on and there was too much space between him and Pinnock for Dornelly to create the equaliser. Found it tough against the impressive Hayes but did enough in the second half to limit the threat... 7 Photo: Pete Norton