https://publications.parliament.uk/pa/cm201719/cmselect/cmcumeds/365/365.pdf
https://ec.europa.eu/commission/sites/beta-political/files/aviation.pdf
https://www.gov.uk/guidance/status-of-eu-nationals-in-the-uk-what-you-need-to-know
http://www.conservativegroupforeurope.org.uk/wordpress/wp-content/uploads/2017/09/Keeping-the-bridges-open-a-CGE-Policy-Options-Paper-.pdf