How did Robin Hood meet Alan a dale?

He first appeared in a seventeenth-century broadside Ballad, Child Ballad 138, "Robin Hood and Allen a Dale", and unlike many of the characters thus associated, managed to adhere to the legend. In this tale, Robin rescues Alan's sweetheart from an unwanted marriage to an old knight. They stop the bishop from proceeding with the ceremony, and Robin Hood, dressed in the bishop's robes, marries Alan to his bride. In other versions it is Little John or Friar Tuck that performs the ceremony.