https://institute.global/news/brexit-realities-taking-back-control
http://letter_to_department_for_exiting_the_european_union_to_publish_the_findings_of_the_analysis_it_has_carried_out_of_the_impact_of_different_brexit_outcomes_for_the_uk_economy
https://publications.parliament.uk/pa/cm201719/cmselect/cmcumeds/365/365.pdf
https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/695321/An_inspection_of_exit_checks.pdf