AFAICT the answer is "No."
I'd've guessed this would be the general consensus on a forum for science enjoyers, but once again
politics is the mindkiller.
I don't find this claim particularly persuasive; Tavistock did not have any control group nor any randomization process. We could in theory generate matched controls from the set of GNC kids who sought treatment at the Tavi but who never received either blockers or hormones, but the reasons for their non-treatment will likely be confounded with psychological desistance.