This is a hybrid Cotoneaster between Cotoneaster frigidus (Tree Cotoneaster) and Cotoneaster salicifolius (Willow-leaved Cotoneaster). The resulting crosses are variously intermediate between the parents which means that one might look like C. frigidus and another like C. salicifolius.

The distribution of this introduction is concentrated around the south east of England (where most of the Cotoneaster experts live?) and there isn't much at all in Ireland or in Scotland except around Edinburgh.