In most hoverflies you can tell which is the male by looking at the eyes: in males there’s no gap between them, presumably an adaptation because the males spend so much time hovering, keeping an eye out for females or rival males. Helophilus hoverflies are different: the male does have a gap between the eyes, so you have to look at the tip of the abdomen. In the female this is pointed while in the male its rounded off with a genital capsule.
So this is a male Helophilus pendulus, a species name that translates as ‘pendent sun-lover’, appropriate as in summer male hoverflies typically hover, more or less on the spot, as if suspended by an invisible thread.