You asked
Under FoI legislation, who do I need to contact to ascertain the number of NHS numbers issued between 1st January 2012 and 31st December 2015, together with the number of NI numbers issued during the same period?
We said
Thank you for your request. The requested information is not held by the Office for National Statistics.
For queries regarding NHS Numbers, we suggest that the most appropriate people to contact would be NHS Digital (formerly the Health and Social Care Information Centre) or the Department of Health.
https://www.gov.uk/government/organisations/department-of-health
For queries regarding National Insurance numbers, please contact the Department for Work and Pensions.
https://www.gov.uk/government/organisations/department-for-work-pensions