I don't know if that quote is just wrong, only applicable outside London, or the situation has changed since I left the NHS, but I worked in a London hospital for over a decade, and spent a year doing agency in many London hospitals, and the % of foreign nurses was far higher than 27.2%. More like 90%. Sometimes I never saw an English ( white ) nurse.
When I started most agency nurses, which hospitals relied on for staffing, were Australian, but the government didn't like paying agency rates, so they replaced them with permanent staff from Africa and the Phillippines as the pay rates were significantly lower. So low that even overseas nurses wouldn't work for it, and the government was forced to give a substantial pay rise to lower grade ( the ones that did the work- not managers ) nurses.