http://fedtrust.co.uk/mrs-may-in-florence/
https://www.publications.parliament.uk/pa/cm201617/cmselect/cmbeis/909/909.pdf
https://www.nao.org.uk/wp-content/uploads/2017/07/The-Customs-Declaration-Service.pdf
http://www.epc.eu/documents/uploads/pub_7865_realitybites.pdf