I'm pretty sure Hornets are not aggressive and actually pretty useful to have in your garden as they are great pest controllers.
I've always been of the opinion that hornets actually ARE aggressive, and very territorial and defensive around food sources. Bees aren't aggressive and do a lot of good however...
Though I've been stung by one so am probably biased!
Are they not 'ornets over your side of the pond in which case you're messing with a completely different species![]()
I'd have a hunt about in your loft, Go up there when it's bright & Sunny as this will show any gaps. Could be burying in & making a nest, Looks like a Queen to me.
I've never seen a wasp that size, nor that dark.