Pitchouette...sorry, wasn't having a go...!
If you are worried then go to the GP...as for those charts...a load of tosh in my personal opinion....but I think it depends on why a child was on a certain percentile...a lot of milkmonsters are sometimes overly high on the chart, not necessarily where they should be naturally (hope that makes sense)...so, if they drop down, after dropping milkfeeds and eating a varied healthy diet, then indeed the percentile they drop down to may well be the one they should be naturally on...!
I honestly think, it's best to look at teh child themselfs, and take their eating habits, etc...into consideration, and how much they are active and if teh child looks and acts healthy...generally there is nothing to worry about...but, like I said, if you are worried, then do go see a HV or GP....sometimes our gutinstincts tell us something that our logical mind may can't explain...