We checked the nest box on 10th October (under licence, of course), and it contained 3 chicks! The oldest was 50 days, so it should be fledging in the third or fourth week of October. The youngest should fledge in the first week of November. Regular watchers will know that the young owls clamber out of the nest shortly before fledging, and can be seen sitting on the box or on adjacent branches in the evenings.
We were watching the nest box last night and one of the chicks kept popping out stretching their wings then going back in again. We saw it do it three times before the light faded so could be fledging soon!