Small black and white bird with long tail feathers.
No interactions present.
This is a Pied Wagtail and death could be a whole number of things. Most probable answer is simply not finding enough food and the time of year. But it could also be disease or have a injury of some sort.
Hopefully it was old age, peacefully in his sleep.
(yeah I know, probably not but.......)
Lat/Lng: 51.4, -2.6
OS grid ref: ST5975