I’m in London and anyone with a blue badge can use the space, some spaces are put in when a disabled person lived there but a lot of the time they no longer do. I think if you neighbours know that the person who lives there is disabled then it’s bad form to park there or have friends park there but essentially the space is for any disabled person so if it’s empty another disabled person is justified to use it. They often aren’t directly outside the home either. I live in a small estate and people use the disabled space who aren’t disabled knowing I do and even though I contact the housing company there is nothing they can do and traffic wardens don’t come in to fine them. So it’s bad form from the neighbours but I wouldn’t feel hurt if another disabled person used it as they have a badge for a reason as much as I do.