Caterpillar was on a thistle. It did not move. Approx. 6 cm. long. Only the one seen.
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This looks like a fasciated thistle to me. I think what you see as a caterpillar, is actually a deformed inflorescence.
Lat/Lng: 55.603, -1.8959
OS grid ref: NU066343
In vicinity of St. Cuthbert's cave. This is rough land with outcrops of rock,furze and woods. Many thistles in area.