The 2-1 success at Rodney Parade, sparked by a goal from loanee Hallam Hope and secured by Matt Duke's penalty save in the final moments, gave the Cobblers a boost in their fight against relegation and also put King firmly in the frame to succeed Aidy Boothroyd on a permanent basis.
"I've loved it," said King after the game. "I've got my spark back.
"I always knew I am a manager, but I didn't shout it from the rooftops because there was no point because no-one was listening."
King also felt his side deserved their change of luck which came when Duke saved Andy Sandell's spot-kick.
"If we had got a lucky result I would say so, but we created a lot of chances and probably could have had a couple more."
Home boss Justin Edinburgh felt his side created 'enough chances to win three games' but refused to be too downcast afterwards.
"We win and lose as a team. We can defend better and we can attack better."