Deschampsia flexuosa Wavy Hair-grass CC DD N
This is a fine leaved quite dark green grass with very light, small and well spaced out flowers. It isn't very tall reaching an maximum of about 50 cm at most and likes to grow on acidic soils. There are a few of grasses with structures like this where the actual flowers are many but individually so small that a still photo doesn't do justice to the plant which looks at its best when moving in the wind.
Not quite as ubiquitous as D. cespitosa (Tufted hair-grass) in that parts of central Ireland and central east England have few records, this nevertheless is a common grass of the British Isles and Ireland.