I left home early this morning as I was attending a training course in Lincoln on marketing, so I didn't have time to replay videos of the night's activities, but yesterday morning's recordings revealed that Nest Box 5 contained 6 eggs, and the great tit was spending some time during the day sitting on them. This could mean that she feels this is a large enough clutch to incubate.
Nest Box 1 has 2 eggs in it. This great tit mother has kept them well covered with moss during the day, so it was a real thrill to make this discovery as she lifted off them in order to leave her home, perhaps to get some breakfast!
I'm going to have a peep at my feathery neighbours before I retire and I'll keep you posted in the morning. Sleep well.