Wulnoth was a Saxon farmer, the husband of Edith and the headman of his village in Northumbria in 1066. When Eldred reported finding a large box on the beach, he went to look for himself, but it was gone.
When Vicki Pallister and Steven Taylor were captured by Eldred, he questioned them. Based on his wife's account of her meeting with the First Doctor, he believed their claim that they were just travellers, despite Eldred's protests. He had Edith give them food for their journey.
After Edith was attacked by Vikings, he led a group of men to find them. They fought, and when the Vikings ran off, Wulnoth brought a wounded Eldred to the monastery.
He believed the First Monk's story of ships coming with supplies and agreed to set up a beacon for them, not knowing they were, in reality, a Viking fleet. However, Edith told him that the Doctor had warned her that a Viking fleet was coming. When Eldred returned from the monastery reporting the presence of Vikings, Wulnoth led his village in defending against the Viking attack. (TV: The Time Meddler)