John laid this down on his screen :
Surely it depends on the lamp shade or fitting. Some may keep natural light
away from the sensor.

If the sensor can ignore its own light then how can it detect the daylight of
the morning - I guess it would only be a simple photo cell.

I don't quite follow your question...

It is simple electronic logic, as in - If light has been turned on,
then ignore input from p/cell until light times out and goes off. If
light is out then enable p/cell.

--
Regards,
Harry (M1BYT) (L)
http://www.ukradioamateur.co.uk