Grey Dagger

I noticed this moth larva enjoying our Victoria Plum on Sunday. It's a Grey Dagger, Acronicta psi. Its close relative, the Dark Dagger, A. tridens, is impossible to distinguish as an imago (unless you get up very close and personal, and examine the genitals). The larvae are, however, easily told apart.
It is common, being found throughout the UK, with a predilection for most deciduous shrubs and trees.