Thanks Pinto. The one thing I can rule out is mould, this is a big open house in a crime free neighbourhood so it is never fully closed up.
It may be time to move out of the main bedroom, I get lonely there, there is one plenty big enough for me and the puter out front, on the upper level with a big sliding door to the sea breeze which is only closed in bad weather. I've needed a reason to clean it out, so I'll start there.
The upper bedroom is shown here. GE have updated the Street View, I'm the grey-headed old bugger watering. 'Tis odd but the previous view showed me watering the footpath. OK. There is no reason to be showing this but I did mention "lonely" earlier.