Unlike the upper Ock, it is easier to get close to the waters edge and there are definitely signs of water voles along the entire length. Including lots of burrows:
With signs of feeding
And what appear to be latrines - used, like lots of mammals, to mark the edge of territories.
And eventually a few sightings, even if good pictures are somewhat hard to come by:
The water vole map is once again updated with these sightings:
View Water voles 2010 in a larger map