https://www.nao.org.uk/wp-content/uploads/2017/07/The-Customs-Declaration-Service.pdf
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/224244/evidence-british-influence.pdf
https://www.vdma.org/v2viewer/-/v2article/render/21059151
https://www.ifs.org.uk/publications/10302