In reply to Bottom Clinger:
One weekend morning we went searching London's Hyde Park for a tree with a Little Owl in it.
There are several pairs of Little Owls with established territories in Hyde Park. We were looking for a pair with a territory "in an oak tree just north of the Albert Memorial".
We watched one Little Owl for an hour. It was perched thirty foot up, as described, in a tennis court sized triangle of grassland between the tarmac paths where hundreds of people were walking, running and cycling.
Ralph Hancock has an birding blog for Hyde Park with Little Owl sightings:
https://kensingtongardensandhydeparkbirds.blogspot.com