M. violaceus, I think, on head shape.
No interactions present.
There has been some discussion in the last couple of years of problems in the identification literature for M. proscarabaeus and violaceus. I can't tell you which this one is. I can only say be cautious about giving it a species name.
I hadn't realised what a problem differential diagnosis of these two species was. I based my ID on a Buglife web page from last year and on colour. I am posting a further photograph which shows the pronotum in considerable detail and which, I think , clearly shows the transverse depression at its base as described in the BW feature.
Hampshire Dragonfly recorder
Hampshire & IOW Wildlfe Trust
Lat/Lng: 50.9701, -1.9192
OS grid ref: SU057189