There's plenty of this about on the Lewes Brooks RSPB reserve. It is one of our commonest rushes: Hard Rush, Juncus inflexus. The inflorescence appears lateral, but in fact the apparent continuation of the stem is the bract.
It is similar to the also common Soft Rush, Juncus effusus, but the latter has a smoother surface and continuous pith, whereas J. inflexus has a greyer green harder stem with 12-18 longitudinal ridges and interrupted pith.
In t' olden days they would be used as candle wicks.