You asked

I would like to request the following information which will prove vital for my work and the case study more specifically. I am interested in knowing:

  • The number of UK passports held at current (or as recently as can be retrieved)

  • The number of passports issued each year for the last 5 years (from 2012-2017 or 2011-2016 if this is too recent)

  • The number of UK passports issued specifically from Sept 2001-2002 (following 9/11) and then 2003 figures to compare this for analysis

We said

Thank you for your request. The latest information we hold regarding passports are from the 2011 Census. We do not hold any more recent information.

https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/populationestimates/datasets/2011censusquickstatisticsforenglandandwalesonnationalidentitypassportsheldandcountryofbirth

We do not hold any information about the number of passports issued. We suggest that you contact HM Passport Office (part of the Home Office), to see what they are able to provide.

https://www.gov.uk/government/organisations/hm-passport-office

https://www.gov.uk/government/publications/hm-passport-office-february-2017