Thanks for your reply. I have checked the HDMI CEC setting on my TV and this is already switched off.
I do seem to be picking up programmes from 2 transmitters on this TV – one being Yorkshire/Lincolnshire and the other East Midlands. In the town I live in you can actually pick up programmes from 3 transmitters depending on whereabouts you live in the town and strength of signal. They are those two already mentioned before plus one being the West Midlands. Would deleting some of the channels help matters?
Tune to the transmitter your aerial is pointing at, the compass bearing from your location for each available transmitter is listed on the DigitalUK web site.