Dark dagger moth caterpillars

I was so pleased when Jamie spotted these colourful caterpillars on our raspberries. They are only very small. They were identified when I got home as Dark dagger moth caterpillars Euproctis similis. The hairs are an irritant and so should not be touched.

 

They don't cause a lot of damage as they're tiny, but I guess if there were a lot of them...