Eleocharis quinqueflora Few-flowered Spike-rush CC DD N
The spike rushes need careful examination before venturing an identification because they have very few distinctive features. This one is tufted and has a flowering spike on the end of a thin green filament about 10 to 20 cm tall but so do some other spike rushes. This was, fortunately for me, identified by our expert botanist guide on a WFS trip to Teesdale. "Few-flowered" may be its name but this plant had more than 20 spikes so if you didn't know you'd expect it to be called Many-flowered Spike-rush.
E. quinqueflora is often found in Wales, Ireland and throughout Scotland but is scarcer in England.