http://www.cer.org.uk/sites/default/files/insight_js_st_9.6.17.pdf
http://www.cer.org.uk/sites/default/files/insight_JS_9.5.17.pdf
https://www.gov.uk/government/news/david-davis-speech-at-ubs
https://publications.parliament.uk/pa/ld201719/ldselect/ldeucom/129/129.pdf