Thanks for all the replies! Some of them really made me laugh 
To answer some questions, until she said what she did at the weekend, it wasn't obvious it was directed at him specifically so we've just ignored. But it was a lot more obvious after her saying what she did.
It's only a small pub. There's no dance floor as such but people do get up and dance. She's usually there with a couple of friends and they almost put on a 'floor show' giving each other brief, fake lapdances (I know, classy...)
As for the twerking, she does it all the time. Going to the bar? Stop and twerk. Going to the loo? Stop and twerk. Out for a cigarette? Stop akd twerk. Sitting down for 10 mins? Get up and twerk... you get the picture.
Tbh, most of the people in the pub are in their 50s and 60s. It's not really a 'young person's' place. I'd just kind of assumed that she was doing it because, despite being gay, she's internalised a need for male validation and, being so much younger than everyone else there, has assumed that automatically makes her more desirable than the men's partners. Judging by the responses/reactions of the men in general, that perception exists largely in her head.
I wouldn't want to say she was 'repugnant' or criticise her looks because, being blunt, she isn't attractive and it would just be cruel.
Her behaviour is irritating and clearly attention seeking. She doesn't get a rise out of anyone it's just intrusive on a might out. But after saying what she did at the weekend, she seems to take being gay to mean that her behaviour was acceptable because she wasn't a woman I'd have to worry about and was all over him and hanging around us. It was just irritating.
Tbh, I wish I'd just said, "Yeah, that's not the reason I'm safe..."
I might suggest we sit with our backs to the room next time, but then we'd just be closer and wouldn't have a table between us and her!
My person reaction would be simply "mate no, you're making yourself look like a cunt".
Maybe that's the way to go...
Yeah, it's totally cringe worthy!