Is there any legal requirement for the NHS to provide single sex wards?
The NHS (along with many organisations) is acting as though the forthcoming legislation on the Gender Recognition Act is already in place.
For anyone who doesn't know, it is proposed to introduce legislation allowing anyone to self-identify as the opposite sex without any medical diagnosis/treatment etc. This NHS Trust is already using self-ID (ie allowing people who are legally still male to be accommodated on female-only wards).
It has also been proposed to remove the provisions in the Equality Act which allows single sex services to exclude (or make alternative provision for) transwomen where it can be demonstrated that it would have a disproportionately negative effect on women.
So, in this case, currently if they could demonstrate that housing this biological male on the women's secure ward would be greatly distressing/detrimental to the women on there, it is legal to, say, offer the biological male a private room elsewhere. However, if the legislation is passed, even if it could be demonstrated that this would have a major negative effect on women and the trans-identified male would only be minorly inconvenienced by being moved to a different room, the biological male would have priority and the service would be breaking the law in trying to meet the needs of women patients.
Like I said, though, many organisations are already being oh-so-progressive, acting as though the law has already being changed and ignoring those "silly, bigoted, hysterical" women. 