I've only recently (2020) identified this Downland Bee Fly. It is a very rare species and feared extinct until 2000. It is still listed as endangered, but becoming relatively more common in the last decade. Like other Bee Flies, it resembles a bee as a form of defence. This one was found in the brambles by the Rotunda (the other side of the ha-ha). That area was cleared the following year, so hopefully it has grown back now, it was a great spot for insects.