Further reading and resources
The Equality Act 2010
The Gender Recognition Act 2004
A v Chief Constable of West Yorkshire Police  UKHL 21
The landmark House of Lords case. This held that a transgender woman can be viewed as a woman for the purposes of the Sex Discrimination Act (since replaced by the Equality Act 2010). Predates the GRA, but we still represents good law:
MB v Secretary of State for Work and Pensions (Case C-451/16)
This European Court of Justice case, postdating the GRA, held the failure to treat a transgender woman without a Gender Recognition Certificate as a woman for the purposes of the EU Social Security Directive was direct discrimination on the grounds of sex.
A Practical Guide to Transgender Law:
Robin Moira White & Nicola Newbegin
The best general reference to transgender law, written by practitioners in the field, recently published.
Update: November 19 2021
An update to A Practical Guide to Transgender Law taking account of recent cases etc and including a new section on Northern Ireland
Transgender Law in Practice: Highgate House Residential Weekend 2020 - Summary from The Inner Temple Yearbook 2020–2021.
A useful summary of some key points:
Sex and Gender Equality Law and Policy: a response to Murray, Hunter Blackburn and Mackenzie
Cowan et al: Edinburgh School of Law Research Paper No. 2020/04
A response to claims that the interests of trans women have begun to erode the interests of 'non-trans' [i.e. cisgender] women and refutation of claims of policy capture.