“The Welshmen did good service in a garden where the leeks did grow, wearing leeks in their Monmouth caps.” Henry V, Act IV, scene vii.
Patron saint of Wales, St. David, is said to have been a sixth-century Celtic priest active in Cumbria. But why a leek? One tale has it that in about 540, the Saxon invaders were advancing to the Welsh border. Uniforms being unknown in those far-off days, St. David advised his Welsh warriors to wear leeks in their caps to distinguish them from their foes.
Another story has it that the battle between Saxon and Welsh was fought over a field of leeks, perhaps under the leadership of Cadwalladr when he defeated the Saxons near Hethfield, or Hatfield, Yorkshire in 633. Needless to say, this is denied – by English historians.