At least, I think it would be.
These are the requirements for one of the most sought after careers on the planet: the chance to go into space. The European Space Agency has announced that from May it will be recruiting a new cohort of astronauts. But although the ESA has said it will consider applications from all 17 EU states, unless the UK government changes its position on funding human spaceflight any British applicant selected would be blocked from beginning the training.
The Constitution they\’re pushing through right now bans discrimination on the grounds of national origin. Thus the proposed action would be illegal.