Hi sorry but I was thinking exactly the same as theemx. We have had them in our garden before I am sure they are not hornets. They are definately a type of bee they bury in the ground to lay eggs maybe

not sure why but they have always been completely harmless to us and the children, don't know what they would do if a dog started sniffing around them. I would just keep an eye but go about your usual business.
Hornets are huge

and very wasp like! Not known one to sting out of spite but I wouldn't trust them at all, they are far to big and mean looking to be friendly :-D :-D :-D