found in garden in wiltshire, england. about 15mm-20mm long. Resting at 6pm on raspberry plant.
You have found Smerinthus ocellata, the Eyed hawk moth. It is name comes from the eyes on the hindwing, which do not show at your photo. It is known to show these eyes if disturbed, to scare of attackers.
The forewing shows considerable variability, as you can see here