[DTV]

I'm guessing that as they'll be getting a new set in the not too distant future they've decided not to bother replacing those screens.  Potentially the new set when it arrives may make the studio feel slightly bigger, as currently the sides are angled due to needing to accommodate those rear projectors.

I'm not sure how the set is oriented, but the studio in trapezoid in shape, it might be that the side walls are angled in line with them? Though, of course, a screen at an angle is a frequent method of rear projection.

Given the studio's small size and unusual shape, I won't be surprised if Norwich sees a small level of deviation from the standard set.