TTT - "ellipsis: "Wouldn't you feel aggrieved at the registrar's behaviour? " - yes, but if I knew in advance that this would be the case and I turned up just to be "outraged" then I would not expect any sort of support."
If the couple knew in advance that the official was not going to be doing her job based on her illegal prejudices, then I don't imagine they would have turned up at all.
It does appear that they turned up to be issued with their licence, as they are entitled to do under the law, and were refused by an official deciding to use her own bigotry to refuse to do the job for which she is paid.
Understandably the couple became upset, and although I would not condone shouting at the employee, it is understandable, given her refusal to offer a legal reason why she would not be doing her job at that time.