The case of 33-year-old Brandon Lee, the school-based Pimpernel who got away (well, almost) with pretending to be a teenager, is a timely reminder to us all. Accurate record-keeping is so important but is it possible that the cunning and ambitious Lee may represent only the tip of the iceberg.
If you've been harbouring doubts about the boy with a beard and a bass voice, or the girl with middle-aged spread, then now is the time to act.
Here are a few tips on what to look out for when identifying an imposter or to use the latest jargon, a "Brandon", who may have illicitly entered your institution.
* At parents' evening you notice his parents are both octogenarians
* He drinks beer with his packed lunch
* In football matches he is very strong on the high ball
* His school uniform is too tight
* In the nativity play he is the most convincing Joseph you've ever seen.
Bear those things in mind. Keep your school Brandon-free.
Jeremy Davies is a former English teacher in south London.