Swimming amidst the tadpoles/frogs. Judging by size, shape, antennae etc Acilus sulcatus is a possibility (at least of those on Plate 17 of the Collins field guide.)
No interactions present.
An Agabus or Ilybius.
Lat/Lng: 53.8568, -1.7733
OS grid ref: SE150400
Small freshwater pond on moorland.