Guys, consider that the Romans in Britain did use composite bows. There have been archeological finds that prove this, wet climate or not.
Look to some ancient Irish legends of Fin and the Fianna. I believe that these stories may have influenced Arthurian tales and the Robin legends. Finn MacCool or Finn mac Cumbhaill was a great warrior with an equally great band of followers. To become one of the band, you had to stand in a hole up to your waist and with only a shield and a stick, you had to fend off 9 spears thrown at you, and even a scratch would disqualify you. You had to jump over a stick your own height, and you had to duck under one at knee level. You had to remove a thorn from your foot with only a fingernail while running as fast as you could. You had to be able to recite poetry, and you had to take oaths that you could never break. They lived isolated in the forest from society and renounce home and family. It was a strictly male warrior society, so no Maid Marion.
I just read that Robin may have been based on a bandit named William of Kensham, aka Willikin of the Weald. And he may have been based on Norse gods, including one named Ull, Hollin, Holler, Oller, or Vulder, who was a god of archery.
Whoever Robin was, he was pretty good with his weapons. And this legend may go back far, far before William showed up and wacked Harold Godwinsson, if you can believe the William of Kensham who was apparently harassing and raiding the French in the wake of the invasion by the Normans.
PS Sorry Yeomanbowman, didn't see your comments. I agree with what you said about the Romans.