Large caterpillar

Large caterpillar

Observation - Large caterpillar - UK and Ireland. Description: My neighbour's cat was 'playing' with 3 of these in my garden. I managed to rescue and move them. Head on its camouflage looked like a pair of big eyes. Size was about 2 to 2.5 inches long. What is it, please?

My neighbour's cat was 'playing' with 3 of these in my garden. I managed to rescue and move them. Head on its camouflage looked like a pair of big eyes. Size was about 2 to 2.5 inches long. What is it, please?