Well, a lot of English infantry seem not to have used shields at all, other than small bucklers which seem to have been a plain red or brown with metal reinforcement – for instance picture
There is 14th-century evidence for pavises bearing St George's cross or the royal arms:
"Robert Mildenhall … received in 1351–3 from John of Cologne, the king's armourer, 1,040 pavises painted white with an inescutcheon of the king's arms surrounded by a garter in blue, and 100 large pavises of burnished silver gilt, with the king's arms in the centre of each under a
garter, and one pavise with the king's arms quarterly from Sir Thomas Rokeby. A second group of these pavises which never came to the Tower but was issued directly to the fleet is described in Cologne's account, ‘1,358 pavises of board, covered in bronze, painted blue with an escutcheon of the arms of St George in the centre of each pavise,' issued to William Clewer, clerk of the king's ships."
- from PDF link
From the same source:
"In the inventory of 1324 sixty ‘large targes painted with the king's arms, £24.00 GBP' (8s. each) were purchased for the Bordeaux campaign, and shipped to Gascony … in 1337 were
twelve targets newly painted with the king's arms." Targes or targets were usually infantry shields.
