Sorry I should have made it clearer, for lack of a relevant NOTAM handy I searched for this one which I remember having seen posted on here before. Just copy pasted it in, the date format is 8 Mar 04 to 14 Mar 04 so not a typo.
I live only a few miles from Sennybridge and yes it is a fairly rural area. However as was pointed out these do have a fairly large impact; for example aside from aviation (where I've only experienced a signal loss while VFR where it's fairly insignificant) the Brecon Beacons are nearby and climbing around the area I've come across a few puzzled hillwalkers who've got annoyed with their 'broken' eTrexs.
It's just a suggestion why there might be a signal loss in one particular area. In probably 7 or 8 years using a GPS both outdoors and in aviation it's the only time I've seen one fail