英国、ＮＡＦＴＡ加盟も　ＥＵとの交渉決裂なら＝テレグラフ紙
https://jp.reuters.com/article/panasonic-idJPKBN1CF1CH

↓おそらくこれが元ソースだと思います
Britain could join trans-Atlantic trade alliance bigger than the EU if there is no deal on Brexit
http://www.telegraph.co.uk/news/2017/10/10/britain-could-join-nafta-trade-alliance-us-canada-mexico-post/