Down are level with their Ulster rivals Derry on six points having played a game more thanks to yesterday's win in London.
The Exiles had the better of the early exchanges, but Down edged ahead thanks to an Eoghan Sands goal on 11 minutes.
It was nip and tuck throughout the opening quarter of the game, but Down began to take control approaching the break with Oisin McManus prominent to help them into a 1-11 to 0-9 lead at the half.
The Ardsmen pushed on upon the resumption with McManus, Danny Toner and Pearse Óg McCrickard all raising flags to move them 10 clear heading for the home straight. McCrickard was to add a second goal with 12 to play as the points continued to flow, with Ronan Costello getting in on the act.