Today I confirmed that Mother Goose had not just left the nest for a prolonged feed yesterday but had actually abandoned it.
I had visited the nest several times yesterday, and each time it had been vacant. This morning, around 08:50, I took the picture here, which seemed to confirm it had been abandoned.
This leaves a bit of a mystery. Did the oiling of the eggs last week been a cause of the abandonment? Did the mother goose detect that the eggs were no longer live? Did she find the oil unpleasant? The plan had been to leave one egg to live and so replicate the situation last year with just one young.
It seems too late now to expect a second clutch to be laid, but we shall have to wait and see what happens.