based in london, the tavistock sees 2000 children a year and last year they took around 300 children figure that's rising all the time. today is mienna and dexter's fourth visit and even though he's only seven, mienna's is worried about puberty kicking in. she does not want to let him down. for us, the thing we needed confirmation on from tavistock was, am i doing the right thing by being so accepting of him? sometimes you need the confirmation and reassurance from a professional. with dexter getting older, it's a race against time to get him the hormones he needs to block his female puberty. and mienna wants to know if this practice will be safe. it's fair to say that the evidence base in this area is poor. but as far as we know, this is a fully reversible treatment. as far as we know, the long—term implications in terms of health seem to be positive. as i say, we don't have full evidence. we must be realistic. at the moment, there is enormous interest in gender. we always have and we continue to work carefully to ensure young people and their families are fully aware of what they a