No interactions present.
It was quite small - about 25mm across, so as you say, much smaller than a peppered moth. Thanks!
An indication of size is often important when seeking insect IDs (although I am as guilty as anyone of failing to provide it).
A nice guide to mothing in the Scottish Highlands is here - http://www.birdguides.com/webzine/article.asp?a=2874.
Has a picutre of a dotted carpet towards the bottom to help with this ID.
Lat/Lng: 57.2, -5.7
OS grid ref: NG8128