You may be looking for Daniel Eldred, a rocket scientist.

Eldred was a Saxon farmer from Wulnoth's village in Northumbria.

In 1066, he found the Doctor's TARDIS on the beach. When he discovered Vicki Pallister and Steven Taylor in the forest, he captured them and brought them to the village, believing them to be Viking spies. He disagreed with Wulnoth's decision to let them ago, warning him that he would regret doing so. When the village was plundered and Edith attacked, he believed the travellers were responsible.

Eldred was injured fighting the Vikings; Wulnoth brought him to the monastery so the Monk could take care of him. When he saw Vikings in the monastery, he escaped to warn Wulnoth, which strengthened Edith and Wulnoth's mistaken belief the Monk was in league with the Vikings. (TV: The Time Meddler)