While White population declined in some areas, in many the ethnic character is more likely to be mixed than dominated by one non-White group only. Source and Figures from Johnston, Poulsen and Forrest, 2014.

London, using 2001 and 2011 data, exhibits extensive clustering of ethnic groups. For most groups, areas in which they were clustered expanded, but not to the same extent as their numbers. Spatial extension of clusters directed towards suburbs where, contraction of White clusters occurred.

Categories are also fluid. Simpson, Warren and Jivraj (2015) show that in England and Wales 4% of all people chose a different ethnic group in the census of 2011 than stated in 2001. e.g. Black Caribbean group, especially young adults, some tend to self-identify as of Mixed ethnicity.

England’s multi-ethnic neighbourhoods are highly stable. 88% of multi-ethnic neighbourhoods in 1991 retained their status in 2001. While over 95% of 2001 remained highly diverse by 2011. (Catney, 2021).

ONS mentions "classifications between 2011 and 2021 are described as only "broadly comparable" rather than fully comparable" and that "instability of ethnicity measured in the national census" doubled between 2001-2011 compared to 1991-2001." NHS, DfE, Police facing challenges mapping to Census.

Ethnic groups and changes categories:
2001> Mixed ethnicity categories, Asian British and Black British
2011> Chinese, Arab
2021> Roma, Black African