The declaration of the Political Declaration, which sets out the framework for the future relationship, note 63, according to which “the parties also agree to consider social security coordination in the light of future passenger transport”, would oblige the UK to take into account the increasing fluidity of EU labour markets. An important limitation of bilateral agreements as part of a future relationship between the UK and the EU is that they only coordinate the social security and health systems of two countries. Mobile workers between a post-Brexit UK and the EU may have a work biography that takes them to the UK and two or more EU countries. Uncoordinated bilateral agreements should leave gaps in their social security and health care. However, in the event of a no-deal Brexit, the protection of the 900 000 citizens of Poland in the United Kingdom is a top priority for the Polish Government: Regulation (EC) No Council Regulation (EC) No 859/2003 of 14 May 2003 extending the provisions of Regulation (EEC) No 1408/71 and Regulation (EEC) No 574/72 to third-country nationals who, by reason of their nationality alone, are not already covered by those provisions OJ L 347, 31.12.2003, p. 1. (2) OJ L 124, 20.5.2003, p. Footnote 65 Coordination regulations developed and refined over more than 60 years provide the most comprehensive and efficient health and social security care for mobile workers around the world. . .