I don't know how to put a link to a newspaper article in Mumsnet however there's a fascinating interview with Richard O'Brien of Rocky Horror Show fame in The Guardian today.
Whilst describing himself as 70% man & 30% woman he states that 'a trans woman can't be a woman. You can be an idea of a woman'.
I don't know if there's a thread about this already.
If there isn't then could someone put a link up for others to read as it's a refreshing read. He even sides with JKR in a roundabout way!