From Tortoise, journalist Polly Curtis tells the story of the Gender Identity Development Service for children and young people at the Tavistock. The Tavi, as it’s known, is the only NHS clinic in England and Wales which treats children suffering from gender dysphoria. Its critics have accused it of fast-tracking young people into changing gender. Its supporters argue it has provided help and support, even a lifeline for some. In a few months’ time the clinic will close. This is the story of what happened. New episodes released weekly.