The chicks spend a lot of time preening their new wing feathers and stretching their wings and have just started flying exercises - revving their wings up to full speed - usually while standing on top of their siblings.
The mother is a zealous housekeeper and with all her cleaning the nest structure collapsed so the chicks almost disappeared for a while under the nest material. As they have grown over the last few days they have come back into view.
The parents have been working non-stop bringing in a supply of caterpillars.
It is interesting that the mother has chosen not to sleep in with the chicks on the past two nights. As far as I can remember, she would normally do this only a day or so before the chicks fledge. However, I don't expect these chicks will be ready to leave until the end of the week. I'll get up early and see if I can catch the moment.