[TVenthusiasm]

I have noticed it too - also last week on News at Ten I noticed the lighting look different, with Tom lit differently to how it usually looks lit. 

I don't think they have moved into a different studio, as that is impossible I believe, but there could simply be some work being done in Studio 1, possibly even upgrading the studio. Since they have no other green screen studio to decamp to, this would mean the look of the news programmes could be affect slightly.

I think they may have used the smaller ITV News London side of the set - which is of course directly facing the national set on the other side. Plus with this most likely being the only studio ITV can use I doubt they were doing upgrades.