My Auntie told me that quite a few areas are running on reduced digital power while transmitters are prepared for the switchover. She had a day a few weeks ago where digital was off all together because they'd turned the transmitter off for her area while they worked on it. Since then however, the signal has been better. They did have some people out to "fix" it thinking it was their aerial but they said it was probably because the transmitter was running on 25% power rather than full.
Have to remember, stray high power RF can kill people