England Under-18s scored six tries in a 42-14 win over Wales at Sardis Road, Pontypridd, in the final fixture before the Six Nations Festival.
Leicester Tigers lock George Martin was a late call-up to join the England replacements, while club colleague Sam Costelow kicked two conversions for Wales after starting at fly-half for the hosts.
England led 21-0 at the break with tries from Sam Dugdale, Ollie Lawrence and Tom de Glanville.
Wales responded with two converted tries but further scores for de Glanville, Ollie Sleightholme and Blake Boyland sealed victory for England.
Head coach John Fletcher said: "Overall we are pleased, but we know we can get better and we will get better over the course of the next week heading into the Six Nations Festival."