Graphopsocus cruciatus: first three images. The other two of possible relevance.
No interactions present.
I first saw this creature in a shaded part of our site last year. On the present occasion, it was potentially exposed to quite bright sunlight but kept itself shaded in a folded part of the leaf (ivy). The two other insects, both diptera I think, and with their mouthparts also applied to the surface of the leaf, didn’t seem that bothered.
Two conclusions possible follow: (i) The surface of a dry ivy leaf which appears smooth to at least one pair of human eyes possesses edible structures (fungal hyphae etc.) at a level of detail that insect senses can detect and (ii) having two pairs of wings, rather than one assisted by halteres, can put you on the defensive.
Lat/Lng: 51.4337, -2.7624
OS grid ref: ST470707