Today we switched our monitoring to the box in the front garden to see whether the local birds were taking any notice of it. The good news is that the answer is 'Yes', but the bad news is that the sun, being low at this time of year, is making it difficult to get good pictures.
When it is shining brightly, as it was on this day, then first thing in the morning the beam of sunlight coming through the entrance hole strikes the side of the box and its reflections create quite a dazzling effect. Perhaps I should rotate the box slightly into a more northerly direction to reduce this effect. Later, things improved as you can see below.
At this stage, all the birds look very apprehensive when entering either box.
This one seems to think that another bird is about to come in - it didn't. Subsequent observation has shown us that both boxes are currently being visited about half a dozen times each day.
However, nothing is yet being brought into the boxes, and no birds are roosting in either box at night.