Hello,
far from a confident ID, and yes, a predominantly white Goose is often a 'domestic goose', at least in Europe, but I looked at the pictures again and again, and the head and especially bill shape reminds me of a Greater White fronted Goose, and this seems a better fit than the (often) chunky triangular billed Greylag.
I wondered about the brownish wash to the greater coverts and a hybrid with a Canada Goose came into my mind. It isnt a pure Canada Goose imo, because of the faint yellow eye-ring (a feature of Greylags, hybrids and very few WFG)
And yes, the rump seems slightly fat, but is this exaggerated by posture(hey Alex, in all three pictures?)? But yes, it really has a plumb=domestic goose like rear end
So I agree it's a Canada x Greylag hybrid for me too