Crawling up the shed late at night.
No interactions present.
I don't think that it's a spider, it only has 6 legs.
Trust me on this one Graham
Its a spider of the genus clubiona.
Arachnids are often missing an appendage or two.
Have a look at pictures of clubiona comta and clubiona corticalis and you will see what I mean.
Lat/Lng: 51.5, -3.2
OS grid ref: ST2381