Ds1 and dd went to a nursery which served a huge range of people. Most were non-white and from deprived areas. A lot of single teenage mums. Most of the children spoke English as a first language, but very few spoke London English (they were Caribean, Asian, etc). There were children with health problems, behaviour problems and social problems. There were also some middle-class families, not necessarily white.
The building was a little decrepit, there wasn't much budget for it so almost all the work was done by the owner/principal's family and friends.
By the time the children left for school, they could all recognise and write most letters and figures, they knew all their shapes and colours, they spoke confidentlly and clearly and listened well, and a significant number could read.
My dcs never learned any offensive behaviour or language, and, although I never clicked with any of the mums or had any playdates with the children, my dcs were very happy at the nursery.
The staff were utterly fantastic. Dedicated and proud of their work. Turnover of staff was very low - in the 3 years that my dcs attended only 2 changed, and the others had all been there for several years.
You need to visit a few times and watch the children and staff interacting.