I spotted this pretty little grass in our meadow this afternoon and managed to identify it with some help from a wonderful book, A Year in the Life of an English Meadow. Here's an extract from the web, describing the field wood-rush, or Good Friday Grass.
"Think of hay meadows and the chances are you will think of ox-eye daisy, orchids or birds-foot trefoil, all glamorous plants, but in Northiam one of the species I am always pleased to see again each spring is the humble, widespread field wood-rush Luzula campestris. This plant has a creeping rootstock and so grows in dense patches, and at this time of year the grasslands and lawns are speckled with the bright golden-yellow anthers on the darker background of the florets. Very attractive in a non-flambuoyant way. This is the shortest woodrush in our area (<15cm high), with the characteristically sparsely hairy leaves of the Luzula family. It is one of those lucky species that remains widespread and does not seem to be declining."