Also, there are more Romanians and Moroccans in Spain than British people.
Admittedly given I don't speak Spanish and the layout of the site being difficult I'm not sure what the 2011 Census says (does the Spanish Census record ethnicity?), but from the source I used, which I've not had any trouble with except for certain places most would, I got;
British - 821,000
Arab/Maghrebi - 608,000
Romanian - 65,000*
*This is as far as I can tell considered to be non-Roma Romanians, the Roma population, which includes the Gitano, other Kale Romani and the Romanian Romani are all classified as a seperate group and combined have a population of 748,000.