Once again for the hard of thinking in this thread - The law in the UK is quite specific. If you decide to throw people out for kissing, you had better apply the same standard to everyone. If you DON'T, if you only throw out the gay couples but not the straight ones, you have broken the law and you WILL get your fucking face legally stamped on.
If you don't want to serve gays or asian people or Hindus then CLOSE your business and piss right off. When the owner/operator of a business decides to start selling goods and services then they have to obey ALL of the laws, not just the ones that they agree with. So you do have the right to be a racist prick, but you don't have the right to open and business and run it as a racist prick. Personal choice. You can't ignore the health and safety laws, you can't ignore the licensing laws and you cannot ignore the laws that stop discrimination.
Once upon a time, in the UK (to our shame) people would put up signs in B & Bs and pubs that said "no blacks, no Irish". That is not allowed. And they are not allowed to say "no gays".
If the pub in question ends up in court, they might have to prove that they would treat all couples the same. A notion that makes me laugh as I very much doubt that the imaginary straight couples they have kicked out would not come running to help them.
The only thing that matters is that the standard is the same for everyone. A sign saying you have a right to refuse service to whoever you want is fucking worthless if the whoevers are always people of different skin colours, religions or sexual orientations. So take your silly fucking sign and shove it where the sun does not shine.