Tomato Hornworms have a spike (horn) on their head.

Maybe someone can tell you which caterpillar this is.

What plant did you find it on?

It was on the ground right next to a potato mound which is also close to one of my tomatoes, it was less than a meter away from my tomato plant.

The reason I ask if it could be a hornworm is because recently two of my tomatoes had large chunks bitten from them. The damage could also have been from slugs or the hedgehogs which visit my garden, I am not sure.

Any help with identification of this caterpillar would be appreciated, thank you.

From it's head, it looks like a caterpillar from the Polyphemus moth (Antheraea polyphemus), but I'm not so sure.