ITV/Channel 4 signal break up

[JackFrost]

Had a problem with an upstairs TV/built in freeview box for a few months now. It's connected to the roof aerial like the TV down stairs but unlike the TV downstairs the picture on ITV and Channel 4 channels keeps breaking up. BBC and Sky channels are largely fine although i occasionally get slight interference on these.

 

I've tried replacing the aerial cable (bog standard), retuning it, swapping the two connections over where it's plugged into the roof aerial, I've plugged the TV in downstairs and like the main TV downstairs it is absolutely fine when plugged into the same connection. Only difference is the main TV downstairs has a separate freeview box.

 

I have a PC and Playstation3 nearby but interference from something seems to be the only other thing I can think of, or I need a high quality aerial cable if such a thing exists, may just be a poor quality freeview receiver inside the TV. I understand a signal booster boosts bad signals as well so can't see that doing much.

 

Any other ideas/recommendations?