 He was in France in 1485, and played no part in the Battle of Bosworth Field which signalled the end of the Yorkists and the start of the Tudor dynasty.In the following year, he returned to England and was pardoned by King Henry VII, who reappointed him governor of Guînes (in the English possession of Calais).However, in 1501, Tyrrell lent his support to Edmund de la Pole, 3rd Duke of Suffolk, now the leading Yorkist claimant to the English throne, who was in voluntary exile.