[Stooky Bill]

That's hilarious. 

I think when the BBC first had the back-projection screens in N6 around 1999 which showed the newsroom, they deliberately had a delay on the feed in case anyone fell off a balcony or there was some other incident.

When they altered the image to add some red walls in the newsroom background it all just became a recorded loop.

The other reason they had to delay the background was because the two screens at the back of the set were mirror images of each other. So if someone walked to the right they'd have bumped into themselves walking to the left on the other screen