Do Romani self identify as white in the UK?
All the Gypsies (Romany, Irish, et al) that I've ever known identify as white. I grew up on a council estate that had many Gypsy families and two of my best friends at school were Gypsy, plus another friend later in life. In fact, I've been on the receiving end of anti-Gypsy racism on account of the way many people who didn't live on this estate referred to the whole estate as "the (nasty slur word for Gypsies that I refuse to type) estate" and any kid from that estate got called by that particular nasty slur word. I've been called that more times that I can count, even though I'm not Gypsy.
On the ethnic monitoring forms over here, Gypsies are listed as a white ethnicity, i.e. "white: Gypsy/Roma".
Also, not all Gypsies are Romany Gypsies and many use the word Gypsy to describe themselves. If Gypsy's become a slur word then it's because of people using it as such, like how the word Paki (short for Pakistani) in the 70s and 80s was a very nasty, aggressive slur word but in more recent times has been reclaimed and the younger generation of Desis don't consider it any different to Gujji (Gujarati) which has never been a slur word.
The big difference between racism in the USA and the UK is that in the USA "white" is a single ethnic group and it's the dominant ethnic group. Here in the UK white has never been a single ethnic group. An American may look at a bunch of white people in Britain and think "white people" and assume that none of the group would have any experience of racism. A European would look the same group and see English, Scottish, Polish, Latvian, Welsh etc and would know that the Polish and Latvian in the group (for example) are a lot more likely to have experienced racism than the others and the English person would be the least likely
Also, the legal definition of racism in the UK is treating someone badly or discriminating against them based on where they come from. Skin colour isn't a necessary component of racism in the UK, though of course racism based on skin colour does exist too. If you mistreat or hate someone just because they're Irish then that's racism. And even if you can't tell someone's Irish (or whatever) by looking at them (though quite often you can) you'll know by their name and their accent.
I appreciate that this is a different way of defining racism to how it's defined in the USA, but it's necessary to define it this way in Europe because racism exists between different European ethnicities. I also think some Americans need to realise that the whole world isn't the same as America, especially when discussing complex topics like racism. Racism exists the world over but in very different forms.