A son of Brutus and brother of Albanactus and Kamber.

After the death of his father, Locrinus became the ruler of Wales and Albanactus had been killed by Scotland. After Albanactus had been killed by invading Huns, Locrinus and Kamber joined forces and routed the Huns. Among the captives taken was a beautiful maiden by name of Estrildis. Locrinus wanted to marry her, but he was already betrothed to Gwendolen, the daughter of Corineus.

Forced to honour his commitment to Gwendolen, Locrinus took Estrildis as his mistress and hid her in London. For seven years he visited her in secret, during which time Estrildis bore him a daughter, Habren, while Gwendolen bore him a son, Maddan.

After the death of Corineus, Locrinus deserted Gwendolen and made Estrildis his queen. Gwendolen went to Cornwall and mustered an army, which she led into battle against Locrinus near the River Stour. Locrinus was killed, and Gwendolen had Estrildis and Habren drowned in a river that she decreed would thenceforth carry the name of Locrinus’ daughter. This river became the Sabrina to the Romans, and is today known as the River Severn.

I found a Logres (or Logryn) in Sommer’s work which is said to have been the successor of “Brutus en Bretaigne”, and I guess this could be Locrinus.