The Gender Identity Development Service (GIDS), based at the Tavistock and Portman Trust in North London, was set up initially to provide - for the most part - talking therapies to young people who were questioning their gender identity. But in the last decade GIDS has referred more than a thousand children, some as young as nine years old, for medication to block their puberty. 'Time to Think' goes behind the headlines to reveal the truth about the NHS's flagship gender service for children.