What's the thinking on this?
Oh, I am so looking forward to this being tested in court where a woman goes to these lawyers and asks to be represented. They simply cannot legally refuse - look at the case last week of Ashers bakery refusing to make a cake for a gay couple. There is absolutely no difference legally between these two situations as far as I can see - they are both providing a service business to the public, and as such, sexual discrimination is not allowed.
In practical terms, if I was looking for a solicitor, I would prefer one that took both men's and women's cases - how else could they gain a real depth of understanding of the law. In fact, if a women went to one of these practices, they really are going to have to try very hard, and do everything absolutely by the book, otherwise they are really leaving themselves open to all sorts of malpractice cases.