Not really my area but I'd say it's a hornet or a species of wasp. They are usually home to very small families of wasps not your usual wasps. Try to leave it if you can. I've always found them in garden sheds.
Looks like a 'queen nest' of one of the social wasps. By the colour either Vespula vulgaris or Vespa crabro. They start off small containing just a few cells, and are expanded when the workers emerge. They're often found abandoned in sheds etc when something happens to the queen.