You missed the point. Refusing to buy US products isnt' about whether something is made in the UK

It is about limiting as much as possible to buy products and services from the USA. That sentiment is strong. Also includes tourism. And not just consumers, but also business to business. This is just the beginning.
We don't like rude liars that are insulting, threatening and present bully like behaviour. That is not how you deal in business, that is not how you do politics. The effects of this will be long term. But at least Trump can exclaim he was the best of the best ever worst President, and repeat it several times before his followers.