This afternoon I have been trawling through the images taken in Fay's box in the hope of finding a picture showing that she had laid another egg. What I found was even more interesting.
The whole sequence started in an unusual way with Morgan going into the box when Fay was not there. You can see it's Morgan from his streaky tousled head feathers.
Another view of Morgan's head feathers. Also, he is not fussing around the eggs as Fay would do if it were her.
You will see later why I am confident this is Morgan!
Suddenly Fay arrives in the nest box. She almost seems to fall into the box such is the speed of her return.
Morgan turns to go - and then he must have noticed Fay's "come on" behaviour - or probably more likely, he heard her calls!
She can be clearly seen fluttering her wing feathers in typical begging pose.
Morgan turns back into the nest box and sees that Fay is still fluttering her wings.
He circles Fay while she continues to display.
This is what it was all about - I'm sure Morgan cottoned on quicker than I did!
Then Morgan mounts Fay ...
... and quick as a flash ...
... he does what male bluetits have to do
In less than a second it's all over ...
... and Morgan immediately departs.
Fay is left in the nest by herself to return to normal.
She seems to check that the eggs are still OK.
Then she does a celebratory nesting wriggle ...
... and leaves the nest box.
Some hours later I was able to find the picture I was looking for - Fay now has three eggs! And another one tomorrow I expect!