Just for anyone interested, the transcript is now available here:
committees.parliament.uk/oralevidence/2177/pdf/
Here's a little extract, from Dr Harriet Hutchinson, Community Organiser, Action for Trans Health Durham:
...there is no way of proving your gender to somebody.
The idea of having to prove your gender is very reductive. It forces trans people to conform to stereotypes in order to receive a diagnosis, and then, of course, receive criticism for perpetuating gender stereotypes.
And therein is the problem - the unprovable, the indescribable (without reference to stereotypes) and therefore pretty useless concept of 'gender' (especially when it comes to medicine and the law).