Lisa: I don't know how the 'discriminated against 'right-wing' (antigay?) Christian' in your scenario would react. I don't know any. BUT, if ALL Christians were refused service by the only store owner in town who, as a gay person, banned them from his shop, all the xians I know (me too) would just get in their cars and shop in the next town even though of course refusal to serve them would be neither 'right of fair'. The crux of the matter is - they could and would not instigate proceedings which may result in the gay person's financial ruination.
Cofty: Your question about a shop sign banning black people. Surely this question could only be relevant if todays date was 5/6/64? It is impossible that such a sign could be dispayed in 2014. Black people were banned due to racial prejudice and they couldn't change their skin colour. Adopting an alternative sexual lifestyle is a personal choice. Is it a good comparison?
The Bull's case and my motive for relating it, was that it sets the precedent that discrimination (in this case refusing a gay couple a double room in a guest house) based on one's religious convictions will NOT in the future hold up in court and will be referred to by any defence team. This means that now, any Christian guest-house owner in Britain has only 2 alternatives: to either ignore their consciences or sell up.