Under Surveillance

I was up to my ears in admin and not very mobile after falling down a rabbit hole yesterday when I heard the sound of an unfamiliar twin-engined plane. I ignored it the first and second times but hobbled out to capture it when it made another pass over our property. 

It is a Partenavia P68 Observer. I accessed the Flightradar24 flight tracking service. The plane set out from Southend airport and has been making multiple passes over our area today. I wonder what it has been looking for or recording?