My money is on a marten or mink, depending on the size. According to the Collins guide to animal tracks and signs:
Marten
"They are normally sausage-shaped, 8-10cm long and 1.2 cm across and usually twisted and drawn out to a point. They contain fur, feathers, bonesplinters.....
They are usually deposited on an elevation such as a rock, tree stump, fallen tree"
Polecat & Mink
"have the usual marten shape, sausage-shaped, 6-8 long and 0.9 cm across and usually twisted and drawn out to a point. They contain fur, feathers, bonesplinters.....
deposited very inconspicuously"
Ott