'Rusty-saddled Coach Horse' on the patio

After another very poor showing around Lowestoft, on Tuesday 1st September, where I saw nothing of note despite checking Ness Point, Birds Eye Factory bushes and the Netposts where nothing of note was seen, it was interesting and pleasing to see on our back garden patio at 2pm, a Rove beetle, Erythylinus caesarean (a close cousin of the Devil's Coach Horse) where it raised its rear abdomen up when attacked by Black Ants (Lasius niger). It also started 'preening its wings' perhaps to maybe clean them of the formic acid that the Ants might have sprayed on it? I think I shall call it either 'Rufous-backed Coach Horse ' or Rusty-saddled Coach Horse, settling on the latter nomenclature, unless anyone else knows of an English name for it?