https://www.gov.uk/government/news/pms-open-letter-to-eu-citizens-in-the-uk
https://blogs.lse.ac.uk/brexit/2019/06/26/did-we-ever-really-understand-how-the-eu-works/
http://www.europarl.europa.eu/cmsdata/115748/IPOL_IDA(2017)583130_EN.pdf
https://www.gov.uk/government/uploads/system/uploads/attachment_data/file/680185/Governor_letter_to_CX_-_Feb_2018.pdf