I have never been to UK, except when I traveled through Heathrow, but have a couple of friends who lived in UK before coming to US. He was telling that there was a lot more racism towards Indians in UK. I lived in US for 7 years and never felt any obvious racism towards me.
British were guests who took over our country, took some of us as slaves. Now, when those same people are coming and "taking over" their country, they don't like it.
The reason that there are more interracial couples in UK is because Indians have been in larger numbers in UK for a very long time. Gandhi studied law in 1888 in London. Mahatma Gandhi. Whereas, the immigration to US is a very recent phenomenon (<30 years in large numbers.)