The non white population of Southampton is 7.6 percent.
(source
http://www.southampto...ton_tcm46-167319.pdf)
Of that number a smaller proportion will be children and out of that a small proportion will have rickets.
The Daily Mail headline is misleading because the report focusses on Southampton (but the headline suggests these are national figures).
By even mentioning the fact that many affected children are from ethnic minorities is doubly silly because not only are their figures negligible in the case of Southampton, but they also serve to confuse their readership.
One poor soul wrote:
"It doesn't help when we have all these foreigner coming over here bringing all their Germs and diseases with them. We got rid of this and TB once"
That's one of the great things about the Daily Mail website - hours of fun reading the Ill-inform cobblers posted by their readers.