Sir Blamore was the son of Prince Nestor of Gannes (possibly Vannes in Brittany). He is particularly associated with his brother, Sir Bleoberis; and the two appeared early at King Arthur’s Court having fought for him against the rebels at the Battle of Bedegraine. They were probably made Knights of the Round Table soon afterward.

Family honour quickly brought the brothers into conflict with King Anguish of Ireland when they accused him of killing their cousin. Sir Blamore found himself obliged to fight the King’s champion, Sir Tristram, in order to try and prove the monarch’s guilt. He was defeated by the great Cornishman, of course, and insisted that Tristram kill him. The judges, however, chose mercy instead and, thenceforth, Sir Blamore and his brother became great friends with both Sir Tristram and his Lord.

Blamore was involved in a number of adventures during his career: fighting at the Castle of Maidens Tournament (Edinburgh), searching for Tristram, being defeated by Sir Palomides at the Surluse Tournament (possibly on the Isle of Man). He was also present at the accidental poisoning of Sir Patrise at Queen Guinevere's feast.

Upon Sir Lancelot’s downfall, Sir Blamore and his brother followed their cousin into exile. Blamore was made Duke of Limosin in Guienne, but later, after King Arthur’s death, he joined the group of former knights who became hermits near Canterbury. He finally travelled to the Holy Land on Crusade, where he was killed fighting the Turks.