The Medieval age was a time period lasting 419 years.
A Dracorex came through an Anomaly into Medieval London and terrorised a town nearby. Eventually, Sir William de Mornay set out into the nearby woods to find and slay the Dracorex, and chased it through another Anomaly to the 21st Century.
The Dracorex was taken in by the Anomaly Research Centre until it could be returned to the Cretaceous, and de Mornay returned through the Anomaly to his time. He returned to the Medieval town to inform them that the Dracorex was gone, and he was proclaimed a hero by the townspeople.
At some later point in the Medieval age, de Mornay married Elizabeth Lionel and had children with her.
- The look of de Mornay's armour, and the fact that he spoke in Early Modern English, would suggest that the period in the Medieval ages shown in Episode 3.7 was the late 15th Century.