Up a tree in my sister's garden which backs on to countryside. She has heard owls at night - could it be a owls nest?
No interactions present.
picture not clear.
Tree nesting owls seldom buid their own nest prefering to use old crows nests or holes in trees. They wil use nest boxes if very large.
The 3 owls that occur in urban areas (little, barn and tawny) all nest in holes, so this is not one of them. Most large nests in trees are likely to be crows. A large rounded nest (with a 'roof') would be a magpie. A flat traditionally shaped nest would be a carrion crow. Raptors such as buzzards and sparrowhawks also make large nests in trees but in my experience these are much less obvious than crow nests.
Lat/Lng: 51.5, -2.5
OS grid ref: ST6580