We don't yet 'celebrate' 4th July, but give it time, lol. It seems that we've come to celebrate or adopt most other American things over the past few decades, eg:
High School 'Proms'
Halloween
American TV Shows (not sure how bad this is these days, as I no longer watch UK TV, but it was dreadful when I was growing up in the 1970s, especially American cop shows).
American Popular Music (it particularly annoys me when our home-grown artistes sing in an American accent, very common since at least the 1960s).
Aping of American institutions in our political sphere, eg creation of a 'Supreme Court' by the Tony Blair administration, creation of the Office for Budget Responsibility by the Cameron administration (a wholesale rip of the US Congressional Budget Office)
All-Seater stadiums in football, dumbed-down cricket formats along baseball lines, names on shirts, etc.
Americanisms in our everyday conversation, also American spellings. I'm even guilty of the former myself, often without even realising (realizing) it.....
_________________
On a mountain range
I'm Doctor Strange