Polly Carmichael became the director of the Gender Identity Development Service at the Tavistock in 2009. “I remember our office was literally a room that had probably been a broom cupboard at one stage”, she recalls. But the decision in 2011 to start offering puberty blockers to under-16s, and in 2016 to widen the professionals who could refer a child to GIDS had a major impact. The numbers of people on the waiting list ticked inexorably up, until the clinic felt it could barely cope.

As the increase in referrals to the Gender Identity Development Service increases, the profile of the young people seeking treatment changes too. There are now two natal girls for every natal boy, a complete reversal of what it had been a decade before. Polly Curtis tries to make sense of this change and goes to Blackpool which has the highest referral rate of anywhere in England.

The internal divisions at GIDS and the wider Tavistock centre spill out into the open. Whistleblowers are publicly critical of GIDS. One accuses the service of fast tracking young people onto puberty blockers after just one meeting with clinicians. The senior leadership team at GIDS desperately tries to hold the team together. Meanwhile the numbers on the waiting list tick up and up.