OK, so then assuming the region is correct (defaults to "current region") in your google settings, assuming you are signed in to google (and it likely will default to current region if you are not), then its probably just likely that the US answers are more relevant to your search query.
If its for shopping (probably the main reason for wanting UK results), then the Shopping tab will help keep it to your region - ish. But I find Google Shopping a bit naff TBH.
Also changing the search slightly, eg, adding uk into it, can help, but most SEO plugins that most of these annoying sites us will put common western countries in the metadata anyway.
All search engines work on similar principles, and the global nature of the internet means that its not easy for a search engine to determine what country a site is aimed at (as its very likely its hosted in another country anyway - for eg, the OOF Shop is hosted in the US)