Long-legged insect(?) skating on surface of pond.Four long legs for skating, two very short legs(?) at front end.
No interactions present.
I wouldn't like to say for certain it's lacustris. There are several species that are very similar, and Gerris gibbifer, for example, is quite common in Scotland. Separation of some species is difficult from even close-up photos, and really needs a specimen.
Lat/Lng: 55.339, -4.0099
OS grid ref: NS726068