Beckwith and Johnson netted the goals as the visitors eased to victory at Lincoln City's Sincil Bank ground to push Ian Sampson's men away from the relegation zone in League Two.
The Cobblers boss will have been delighted to see his side build on Saturday's home win against Gillingham and put another three points in the bank as league action takes a break for the FA Cup this weekend.
Reaction to follow on Footy Mad.