Unknown fly

Unknown fly

Observation - Unknown fly - UK and Ireland. Description: Quite of few of these fairly large flies have appeared recently. They perch in prominent positions but fly rather weakly. Most exhibit this curious, 'arms touching' pose. Looks pretty primitive (i.e. early in the phyllogenic order) except for the antennae

Quite of few of these fairly large flies have appeared recently. They perch in prominent positions but fly rather weakly. Most exhibit this curious, 'arms touching' pose. Looks pretty primitive (i.e. early in the phyllogenic order) except for the antennae which are clearly not filamentose. Ideas welcome, I'm stumped.