This is round the back of the cottage with the chimney I photographed earlier. After taking several exposures I noticed the reflection of the sky on the window to the right. I repositioned the camera to fit the window and some of the Milky Way in the frame.
Also an optical phenomenon which is apparent here (that I've never captured before) is the 'Airglow' seen as a green hue in the sky, not to be mistaken for an aurora (I wish!).