Ceci n'est pas une guêpe

Indeed, it is not even an image of one. Rather it is a cleptoparasitic cuckoo bee (Flavous Nomad Bee; Nomada flava).

I won't pretend I knew what it was when I 'captured it on sensor' whilst exploring the grounds of Ashdown House, Lambourne. Its true identity became apparent only after a 'wasted' morning exploring sites devoted to the topic of UK wasps

Allegedly, cuckoo bees of this particular type are "...common and widespread over much of south-east England." (link), but they have managed to evade my penetrating gaze until now