I found it hard to accept that I was being shown a real live moth caterpillar but it was true. The third photograph shows its size and we understand it is not fully grown. The moth itself we didnt see. Its the lava of the Deaths Head Hawkmoth.
More information can be obtained from the Somerset Moth Group.
Top picture by John Bebbington others by Roger Harvey.
Here is a link to a photo showing the moth. Clickhere.