The SA U18’s made the most of their strong forward performance by scoring two tries to one in the first half, while they also landed three penalty goals to build up a 23-10 advantage at the halftime break.
They maintained their dominance in the second half and managed two further tries and a penalty goal, while restricting England to two converted tries for a well-deserved win.
While the SA win was built on their forward dominance, flyhalf Stehan Heymans was equally outstanding with a personal contribution of 18 points via four penalty goals and three conversions.
The impressive No 10 landed three penalty goals while his opposite number Rory Taylor replied with one to make the score 9-3 in favour of the home side halfway through the opening spell.
Visiting flanker Jack Bennet then took advantage of some poor SA defence to run in under the posts as England edged ahead 10-9.
However, that lapse of concentration was enough to kick the home side into a more determined mood as they hit back with some powerful forward carries and strong running in midfield.
Hooker Ethan Bester dotted down for the home side from a lineout maul, while scrumhalf Caleb Abrahams followed him over the whitewash on the stroke of halftime. Heymans added the extras to stretch the halftime lead to 23-10.
South Africa kicked on after the restart and soon raced into a 33-10 lead when replacement hooker Luca Bakkes scored off the back of a brilliant maul, with Heymans again on target with another penalty soon afterwards.
They then also showed the grit needed in defence to keep the English at bay. However, replacement hooker Loic Keasey managed to breach the line for England's second try to reduce the gap to 33-17 halfway through the second stanza.
Replacement lock Jack Waterhouse then showed his speed and power to take a final pass and force his way over for another converted try, South Africa's fourth of the afternoon, to take the score to 40-17.
But England refused to give up and Keasey got his second when he went over to take the final score to 40-24 in favour of the SA U18's.
SA U18 40 (23) - Tries: Ethan Bester, Caleb Abrahams, Luca Bakkes, Jack Waterhouse. Conversions: Stehan Heymans (3), Thurlon Williams. Penalty goals: Heymans (4).
England 24 (10) - Tries: Jack Bennet, Loic Keasey (2). Conversions: Rory Taylor (3). Penalty goals: Taylor.