National Academy coaches John Fletcher and Peter Walton have named a squad of 26 hoping to build on a cleansweep of wins in this season’s Five Nations Festival.
Leicester Tigers centre Joe Cobden is welcomed back after injury and he joins prop Ryan Bower, flanker Matt Everard and fly-half George Ford in the squad.
England play three matches in South Africa against Western Province on August 1, Boland on August 4 and South Africa Schools on August 8.
Head coach Fletcher said: "Development tours like this are crucial to the progress of talented young players. Although playing in the Five Nations Festival is hugely important, players also need to compete against the southern hemisphere teams.
“They are some of the strongest sides around and our players need to get used to travelling and touring as that is what happens in international rugby.
"South African youth and age grade rugby is as good as any in the world, and their school and academy structures are very strong."
England Under-18 squad
Harry Allen (Saracens, Chislehurst & Sidcup Grammar)
Peter Austin (London Irish, St Paul's Catholic College)
Ryan Bower (Leicester Tigers & John Cleveland College)
Rob Buchanan (Harlequins, St Bedes School)
Matt Everard (Leicester Tigers, Wyggeston & Queen Elizabeth College)
Ben Glynn (Bristol Rugby, Filton College)
Alex Gray (Newcastle Falcons, Barnard Castle)
Sam Jones (London Wasps, Aylesbury Grammar)
Charlie Matthews (Harlequins, Hurstpeirpoint College)
Henry Thomas (Unattached, Millfield School)
Joe Trayfoot (Harlequins, Epsom College)
Sam Twomey (Harlequins, Dulwich College)
Billy Vunipola (Unattached, Castle School)
Mako Vunipola (Bristol Rugby, Millfield School)
Joe Cobden (Leicester Tigers, King Edward VI School)
Sam Edgerley (London Irish, Wellington College)
Owen Farrell (Saracens, St Georges School)
George Ford (Leicester Tigers, Rishworth School)
Ryan Glynn (Sale Sharks, Sedbergh School)
Jonathan Joseph (London Irish, Millfield School)
Jake Sharp (Saracens, Oaklands College)
Andy Short (Worcester Warriors, Worcester 6th Form College)
Sam Stuart (Harlequins, Sedbergh School)
Christian Wade (London Wasps, RGS High Wycombe)
Jack Wallace (London Wasps, RGS High Wycombe)
Marcus Watson (London Irish, St Georges College)