I determined that the door was 100% uPVC not metal framed and there does not appear to be any chnage in coupling with the door closed or open. The sealed windows are some metal looking but doesn't seem to effect the loop.
Just thought you might like to see these:
This is the loop on 40m :-)
This is the loop on 30m :-)
The land lord still will not allow an external antenna so this looks like a good option.
BTW the pictures grabbed from MiniVNA Java software. Putting it on a contunous loop makes tuning dead easy.
Not tried a different balun that will give me 10m yet. I used 10 x 400mm legs to make up the loop. I'll post a photo soon.
I'll run it with the FT817 later.