Heath, again, in his ‘Armies of the Middle Ages: Volume 1’ in his notes to Figure 24: pp101-102 (a Welsh ‘foot soldier’ still dressed in just a belted tunic, cloak, no hose/leggings…and one shoe!) states “Welsh contingents in uniforms are recorded as early 1337, these uniforms being described as green and white from 1346.” and “…the Welsh did not fight only for the English. From the mid-1360s they are often to be found fighting for the French too, under such leaders as Owain Llawgoch…Ieuan Wyn and Edward ap Owain”.
No sources are given. I assume the latter was one of the Tudor dynasty, haven’t checked.
None of which is germane to the OP, but we seem to have drifted away from that somewhat.
"I go online sometimes, but everyone's spelling is really bad. It's... depressing."