Found on a wall,dark green to brown,spiky ,small light brown marks along bottom of sides.
No interactions present.
On second thought its not hairy enough.
I thought Red Admiral first too,but its been such a poor year for butterflies here that I discounted it ...maybe prematurly ! certainly the spikyness is more reminisent of a butterfly.
Lat/Lng: 52.6, -7.9
OS grid ref: SF0616