From Heathrow Terminal 1 train to Paddington (H&C Line)-Underground, Tube to London Euston, then train to Northampton. 1hrs 32min £39. From Heathrow Central Bus Station line 140 bus to Harrow & Wealdstone then train to Northampton. 2hrs 19min £19. From Heathrow Central Bus Station line 230 bus to Brook Furlong, Milton Keynes Coachway then bus to Northampton, Coach Park. 2hrs 33min £14. From London Heathrow drive to Northampton. 1hrs 10min £15.