Hornets in Kent - NOT amateur radio

One of our sons who lives near Canterbury, Kent, UK reports lots of hornet sightings this year. Maybe it is as they are quite near to France? Normally they are quite uncommon but he has seen lots this month alone. Of course it could be global warming and we are beginning to see less common insects more often? I have seen a few beetles and flies in the garden that I do not recognise. Perhaps they have always been around. I have asked my son to take some photos.