Sidney Bird

Sidney "Sid" Bird was an evacuee from 1942 Hackney who was sent to live in Hydra Hall during World War II. While playing hide-and-seek in its basement one day, the hall was bombed by the Luftwaffe and a portal was opened to a pocket universe, which he entered.

He later escaped capture from Roman soldiers in the pocket universe but arrived back at the hall in 2022 where he met the Thirteenth Doctor and Dan and was looked after by the hall's current owner, Vera Parker. Eventually, the Doctor rescued Yaz and many others from the pocket universe and closed the portal, allowing the Doctor to return Sid to his own time.

Sid later survived the war and visited Vera while elderly in 2022, shortly after he left. He later gave talks for the Hydra's Gate History Society about Hydra Hall's use during the war. (COMIC: Hydra's Gate)