I wouldn't wish to discriminate against a crewmate who was a member of the BNP any more than I would wish to discriminate against a crewmate who was Catholic, or gay, or ginger-haired, or a member of a BDSM swinger's club. So on that basis, of course I would be willing to work with them. And in the same vein as I wouldn't tell any bosses/colleagues if I had stumbled upon the information that Crewmate X had appeared in an adult magazine, or that he called himself Flora on the weekends... I also wouldn't run to anyone I worked with and say "You know Crewmate X? They're a member of the BNP!" Some things belong in a person's private individual home life and don't need to be spread around by workplace gossip unless they are the ones who choose to make it so. And who wants to get themselves a reputation as a snitch? However. I probably wouldn't be keen to see them outside of work and if it caused too much tension while working I might try to gently and informally suggest to whoever organises these things that we had "a bit of a personality clash". I'd also be keeping my eyes open to make sure they didn't behave less professionally with patients who weren't white British.