Fantastic Caterpillar!

Fantastic Caterpillar!

Observation - Fantastic Caterpillar! - UK and Ireland. Description: I have never seen such a big caterpillar in England before so I was amazed to find this in my garden! If anyone can tell me what it is I would greatly appreciate it, is it an owl butterfly maybe?

I have never seen such a big caterpillar in England before so I was amazed to find this in my garden! If anyone can tell me what it is I would greatly appreciate it, is it an owl butterfly maybe?