Not a hornet! The hornet mimic hoverfly feeds on nectar and pollen when in their larva form they are predators to aphids! It is more than welcome to save our almond tree, our almond tree is covered with aphids! The hornet mimic hoverfly is a migratory hoverfly, migratory hoverflies are often considered the second most important pollinators, after bees! It can grow up to 2cm long! It is rare in Northern England but common in the South of England and Europe! I took a picture of it thinking it was a hornet! Progressing… Treating my buzzing phobia 
Nika Strok Underwood