Jack Nowell scored his third try in two Under-20s matches while flanker Wells also touched down twice as England wrapped up their fourth win of the competition and denied Wales the Grand Slam.
Coming into the match with three wins and one defeat - a one-point loss to Ireland - under their belts, England knew that their superior points difference meant this was a winner takes all clash.
It proved the perfect send-off for Hunter, who was overseeing his last match in charge of the Under-20s before he heads to the Exeter Chiefs, and it was England's brute force up, combined with a defensive line that was not breached, that paid dividends.
Wales began brightly enough and moved ahead when fly-half Sam Davies was on target with the first of his five penalties on the night but back came England with highly-rated winger Nowell forcing his way over on ten minutes after a smart break from scrum-half Callum Braley.
Slade missed the conversion however and Davies kicked the hosts back ahead on 18 minutes from just outside the England 22.
Slade was then wayward with his first penalty effort of the night before a powerful Wales scrum set up Davies for another chance from the tee - one he duly accepted to extend his side's lead to six.
Finally Slade found his scoring boots after England's forwards then flexed their muscles and just before the half-time interval, the visitors' pressure finally told.
As Wales' defence became desperate, Wales No.8 Ieuan Jones was sent to the sin bin and England took full advantage, Wells spinning off a driving maul to touch down.
This time Slade was on target with the conversion to hand England a 15-9 lead at half-time but Davies continued to chip away at the lead, slotting his fourth penalty on 50 minutes.
Three minutes later, Slade responded in kind before he bisected the posts with a fine drop goal just after the hour mark to hand England a commanding nine-point advantage.
Wales refused to lie down however and Davies struck his fifth penalty of the night with 15 minutes remaining to ensure a tense finish with the hosts within a score of the lead.
England set about pinning Wales back in their own half as clock ticked down, aware that their hosts required a converted try to move back ahead, and their pressure forced another penalty with six minutes to go.
Slade pulled his kick to the right and when England had a penalty slightly further out a few minutes later they opted for the corner and it proved the correct decision - Wells touching down from the resulting maul to put his side out of sight, Slade putting the icing on the cake with the extras.