[Stuart]

To put my two pence worth in, there is certainly an extra camera being used, take this shot for example...
up.metropol247.co.uk 
... you can see the autocue hood of the camera used to capture the catwalk just peaking in at right hand edge of the image, so that rules out that camera, but also by looking back at earlier pictures posted of the whole Studio B set up, even though you could say it was taken via the camera usually used for the main monolith and the one which performed the pan for the credits, I just don't think you could get the camera to have such an open field of view to show the ceiling while the positioning of the shot is basically right on top of where the catwalk platform begins and given how far away the track is from the platform, it has to be an extra camera, as others have mentioned, probably not a steadicam, but I could certainly see the model of gimbal suggested.

There are 2 cameras on the 'catwalk track', one of them being able to see the other is not impossible, just poor framing of the shot.

Nobody suggested that the ground level shot was from the single camera on the track in front of 'Tower A', but there is no reason why it couldn't be. They are very versitile cameras which can capture every part of the studio.

Why bring in another camera when you already have 7 covering every possible angle you can imagine in your wildest dreams?