The disappearance of the 15-year-old in December prompted Scotland Yard’s counter-terrorism command to investigate. Pupils were spoken to and seven students were identified as potential friends of the missing girl. Among them were Kadiza, Amira and Shamima although, at that stage, police had found no reason to suspect they were in danger of being radicalised.
Police accept that they wrote letters to the parents saying their children had been friends with the pupil who had gone abroad and asking for permission to take a formal statement. But instead of delivering the letters directly to the parents, police handed them on 5 February to the girls themselves, who hid them in their school textbooks in their bedrooms. The families only found the letters after the girls left on 17 February.
Everything about this story sounds fishy. It makes no sense whatsoever that the police wrote these letters for the parents, yet gave them to these underage girls instead, who (to anyone with half a brain) would very predictably fail to pass them along. Just the simple fact that the police chose to use letters instead of contacting the parents directly (which I'm fairly certain goes against regular protocol), never mind having them delivered in this fashion, is suspect.
<Edit> It's my guess the authorities were hoping for something like this to happen, so they could further their agenda, yet they didn't want it to seem like they did nothing to prevent it in the meanwhile.