My ds is in reception and was evidently measured as part of the National Child Measurement Programme. We got a letter saying he's in the healthy range etc but I thought it was interesting that rather than giving you a centile based on their weight (like those charts in the red book), you get a centile based on their Body Mass Index which seems far more accurate.
He's on the 28th centile which surprised me as I find it hard to believe that over a quarter of kids are skinnier than him (he's all bones and ribs). I found it rather reassuring since I'm always fretting about feeding him up. If you got a letter, were you surprised/reassured/shocked by what it said?