No home comfort for Kings Langley
The first half was an even, if physical, affair, with an early Mitchell Weiss shot parried by Louis Porcelli and Daryl Atkins putting the rebound wide.
As Kings continued to have the better of the first 15 minutes, an Atkins lob drifted over both goalkeeper and bar, while Porcelli did well to save with his feet from a Weiss break.
The visitors then took their turn to have the better chances with Cooper shooting wide when through, a free kick parried by debutant keeper Mayson Tewkesbury and Hartley missing a chance from a poor clearance. The home side finished the half strongly with a good move between Nick Jackson and Atkins finishing just wide and Jack Pattison firing narrowly over.
Dunstable got the perfect start to the second half when danger man Jimmy Hartley had the whole goal to aim at after a shot had been cleared off the line and he made no mistake.
As the visitors seized the game, Cooper missed a good chance, but Atkins was marginally wide when put through and Weiss was again foiled by an brave Porcelli save at his feet.
When Harold Joseph hit the post from a corner, Kings sensed it was not to be their day, and AFC turned the screw.
A shot demanded a full length save from Tewkesbury., and a James Bishop curler sail ed just wide. Hartley put the issue beyond any doubt in the 81st minute.
He hit a power shot to round off an impressive display, and a well marshalled Dunstable defence comfortably contained any sporadic home attacks to seal the points.
Langley were back in league action last night, as they were due to travel to Hillingdon Borough.
On Saturday, they entertain Burton Park Wanderers in the FA Vase (ko 3pm).