I finally had a response from my local library regarding 'Beyond Magenta...'
They wrote:
The function of a library service is to provide free access to a diversity of information, opinion and ideas in a neutral and hospitable environment.
Selection, provision and access to library material is informed by legislation on terrorism, race relations, equality, local government, freedom of expression and human rights and access to information should not be restricted on any grounds except that of the law.
If publicly available material has not incurred legal penalties then it should not be excluded on moral, political, religious, or racial or gender grounds, to satisfy the demands of sectional interest.
On this basis we do not feel it necessary to remove the item from stock. However, we have decided to move it from the Teens section into the Adult Non-Fiction section. This means that it will not be possible for young people to borrow this title on their own tickets.