Pop goes the ?

Weasel? I think so, no black tip to the tail and it looked too small for a stoat.
Moved like greased lightning but kept the gov and me plus two other birders fascinated for about 20 minutes.
Difficult to get a sharp shot because he? was in and out of twigs on the ground and the autofocus was playing old harry.
Tried a couple of manual shots but they were no better. Difficult to focus on a fast moving target the size of a hamster 40 feet away!
Saw lots of birds at Minsmere including about five Marsh Harriers that would have loved this guy for lunch had they not been so busy showing off.