Tufted Hair Grass (Descampsia cespitosa)

This is a very tall (up to 4–5 feet, 120–150 cm) and distinctive grass growing in very large tussocks in moist ground and just now in full flower. There's nothing must else it can be confused with - possibly Reed Canary Grass, but that has less spreading panicles and is much softer. If you run your fingers along the leaves of Tufted Hair Grass, you are liable to end up with cuts!
Malcolm