I live in Shropshire, I think I've had a Hummingbird Hawkmoth in our garden this evening.
There was a large insect moving quite fast and hovering about the potted plants in the yard. It almost looked like a bee
The wings were beating very fast and appeared translucent
The length of the body I'd say was a couple of centimeters at least.
The other option I thought was that it could be a Silver Y moth.
Exciting to see!