This original, screen used giant speaker prop was used in the 2006 Christmas special ‘The Runaway Bride‘ and can be clearly seen in the foreground of the scene where the Doctor utilises the sound system and his sonic screwdriver against the robot Santa’s.

It is indeed giant, measuring 48 inches (128cm) wide, 72 inches (184cm) high and 36 inches (92cm) deep! As a result it wouldn’t even fit through a front door and so is in storage!