Oyster and oysterling fungi can be difficult to identify but I’m fairly sure these are Peeling oysterlings (Crepidotus mollis).
Habitat: ‘usually grouped on decayed wood of deciduous trees, especially Ash and Beech.’ Check.
Gills: ‘radiating outwards; greyish brown with a reddish tint and mid-brown spore print’. Check.
Cap: ‘flat, oyster-shaped or elongated and laterally attached to substrate’. And the clincher: ‘a peelable cap cuticle’. Check.
Information from my trusty Collins Complete Guide to British Mushrooms & Toadstools, Paul Sterry & Barry Hughes, Collins, London, 2009.