“In respect of a young person aged 16 or over, the legal position is different. There is a presumption of capacity undersection 8 of the Family Law Reform Act 1969 . As is explained in [in In re W (A Minor) (Medical Treatment: Courts Jurisdiction)[1993] Fam 64 ], that does not mean that a court cannot protect the child under its inherent jurisdiction if it considers the treatment not to be in the child’s best interests.”