I'm not an explorer and come here to appreciate the photos and the history of these derelict places, and show my support for the intrepid explorers.
But - I remember the places you mention. I used to visit both hospitals regularly and my daughter was born in Harold Wood Hospital - nowadays an exclusive residential area, like so many old hospital sites.
I think previous posts here have covered the old Goodmayes psychiatric hospital in Ilford, but I I don't know if anyone covered Warley in Brentwood or the more recent closure of Runwell Hospital near Wickford
The destruction of hospitals and the loss of so many inpatient beds is criminal, but that's another story.