Hi everyone .... after trawling around the internet, it seems my beetle is indeed
Strangalia maculata, although in some cases I have seen it referred to as
Rutpela maculata – has its latin name been changed recently?
This seems to be another species where the markings on the elytra are quite varied, but everything about it, including the location and the presence nearby of umbelliferous plants, one of its preferred food sources, seems to confirm the identification.