All the hair samples produced negative results.
While this didn’t totally exclude the possibility that the
children had been sedated, especially given the time
that had elapsed, it meant nobody else (including the
PJ and the media) could prove otherwise
[Madeleine]
If it was a fact that it was 100% impossible for the tests to show what had happened 5 (?) months earlier - then there would have been no point in having them in the first place. Of course had the tests revealed positive results then no doubt some sceptics would be claiming that as proof that Kate was in the habit of giving her children drugs IMO.
The negative results showed that not to be the case - which concurs with evidence from other people who knew them well enough to have an informed opinion. I doubt if anyone as health conscious as Kate, that a rich tea biscuit was regarded as a major treat, would be putting even Calpol into her children's systems unless it was really necessary.
IMO