I'm in a more marginal location, com 8 is actually amber on the coverage table, and already had a high gain group A aerial and an amplifier.
I discussed options with the man at ATV (if you want to know more about this stuff have a browse in there: ATV website ).
I could have spent £70 or so changing my aerial for a wideband, but they have lower gain for any given frequency than a correctly grouped aerial, so I might have still have not got com 7 & 8 and compromised some of the other lower powered muxes to boot.
The other option was a group E aerial and diplexer to put it in parallel with my A aerial. Cost about the same as the wideband because the E aerial was much cheaper than a wideband. Needed some extra bracketry of course, but that's not much. So I did that and it worked a treat . Unless there is some reason a second aerial can't be fitted this is the way to go as widebands are basically a compromise. It also means that if/when channels 55 & 56 are discontinued the extra aerial can simply be removed or disconnected (if you want) with no need to change the 'main' aerial. (This might be necessary because if the 55/56 frequencies do get sold off for mobile use you are liable to get some heavy mobile transmitter stuff coming in, either through a group E or a wideband. It might not matter, but if it does it'll be nice to be able to fix it by just cutting a cable.)
The weather. At this time of year it often gives enhanced reception conditions.
You are obviously on the edge of the digital cliff for some multiplexes, which is why they were found when the retune occurred but have now disappeared with changes in the weather.
It is not "weird", it is perfectly explainable.