Ferdinand (The Time of the Daleks)

 was the head of security at Learman's palace. Once he was betrayed by Mariah Learman's allies he joined the rebel forces, headed by Priestly and Hart to fight the daleks supreme rule.

The Doctor set up a spatial corridor from the mirror in his office which provided useful for the Doctor's scheme, as it helped them to escape to the rebels hidey-hole, which then allowed the Doctor the return Charley Pollard to the right time, and also when the Doctor rigged up the a temporary mirror from silver foil, to escape captivity. (BFA: The Time of the Daleks)