Interesting, I saw the same yesterday on the C7. Field Vole I reckon. But could also have been a Stoat.
http://en.wikipedia.org/wiki/Field_vole
http://en.wikipedia.org/wiki/List_of_mammals_of_Great_Britain
On C7 youre near Brooks/River..There are Mink down there(American variety)...Similar to Stoat but thicker and Darker...I`ve seen several in around ditches down there.