Daniel Guinness, all from play, and Pat Havern both hit 0-3 in the first half at Ruislip as the Mournemen went in 0-8 to 0-5 ahead at the break.
However, Down outscored the Exiles 1-6 to 0-1 in the 15 minutes after the resumption with Odhran Murdock firing the goal from a penalty in the 50th minute.
Guinness and Havern both continued to score freely with Miceal Rooney also contributed a series of fine efforts from play.
Even defeat by Offaly next weekend will not prevent Down from topping Group 4 given that they would edge London or Limerick on the head-to-head.
Ruairi McCann’s third-minute goal helped Antrim lead 1-8 to 0-7 at half-time at Wexford Park, with Ryan McQuillan and Joseph Finnegan also among the Saffrons’ scorers.
Wexford cut Antrim’s lead to 1-10 to 0-12 by the 49th minute and while scores from Patrick McAleer, goalkeeper Michael Byrne and McQuillan stretched the Saffrons advantage to four once again, they had to endure a nervy finish as the home side cut the margin to a single point.
McQuillan finished with 0-6 with McAleer contributing 0-3 for the Saffrons, who finished with 14 men after Conor Hand’s black card in injury-time.
Carlow gave Fermanagh a tough game at Netwatch Cullen Park as the Ernemen needed a Conor McShea goal just before the break to go in 1-4 to 0-6 up at half-time.
Josh Largo Ellis hit two third-quarter points following his switch to the half-forward line as Fermanagh led by three after 50 minutes.
A superb score by the impressive Jonathan Cassidy and two late points from substitute Conor Love helped the Ernemen keep their noses in front, with Ultan Kelm’s two second-half scores from play also crucial for Kieran Donnelly’s side.
