Sedge

or so I'm told!
While we were out on our (cold) afternoon walk I spotted a couple of these by the side of the path which is adjacent to an old millpool. I had never noticed before that it was growing profusely in the pool along the opposite bank. I've lived here about forty years and couldn't count the number of times that I've walked this path, I cant believe that I've never noticed this plant before.
I drew it to  the attention of Redilady, knowing that on a dull day like this, we would inevitably have very similar blips.