How often has this happened to you?
I heard a loud noise, which I wondered might be a helicopter, so looked at flightradar, and it is the top flight being tracked worldwide:

(image shows screenshot from Flightradar24 showing helicopter "GHPIN" flying over York)
It was very low and therefore very loud.
Edit: looks like the helicopter belongs to Richard Harpin.
I heard a loud noise, which I wondered might be a helicopter, so looked at flightradar, and it is the top flight being tracked worldwide:

(image shows screenshot from Flightradar24 showing helicopter "GHPIN" flying over York)
It was very low and therefore very loud.
Edit: looks like the helicopter belongs to Richard Harpin.