This is a new species for me and the garden. It's a Tachinid Fly with the scientific name Nowickia ferox. It is a harmless fly, about the size of a large Bluebottle but with an impressive yellow abdomen. At first I thought it was a Hoverfly,  I took photographs and then had it positively identified. It was feeding on nectar from flowering mint. However, what the photo doesn't show is the very interesting and ghoulish life-cycle. Tachinid flies are  "endoparasitoids", that is to say that the maggot stage of the fly develops inside the host, eating it from within and then emerging to pupate. This fly is  also Host Specific to a moth Dark Arches, I would have thought that this makes the very existence of Nowickia ferox precarius dependant, as it is, on the success of the moth which it is totally reliant on for it's very existence.  Again, all this is happening in and around the garden, a fascinating story well worth a lot more study and interest.