Phew! Another St Mary's in Derbyshire (I thought I would only ever have one). [This only makes sense if you are reading these comments in number order, Big Ted]
This is a derelict St Mary's (which is always very sad). I sat on the greenery on a wall for my photo (dodging some very smelly Cow Parsley).
It was a St Mary's Mission Church, but since it didn't know whether it was in "Saw Mills", "Sawmills" or "Ambergate" I can see why its mission failed!
Update January 2021: The church is now for sale as a house! There's not much garden.