The number plate as a licence to park your bike on the premises is a good idea. It might even reduce theft... My sister tells the story that when she started in secondary school, at age 13, she was supplied with a black bike previously used by an aunt... When she to the bicycle shed. All the bikes were black!!! And she could not recognise her one and the one which was left was a decrepit wreck . When our father learned of this he marched her down to a local shop and bought her the brand new "Pink Witch. " .. early swinging sixties!!! . Bright pink bodywork, bright green mudguards, white saddle and a mirror.. . She had no difficulty in recognising her bike since.
I am ambivalent about cycle helmets for adults, but concede they are helpful over young brains, where the skull is still not fully hardened.
Many of the postings on that topic from the roadcc website are off. The headmaster is to be commended for promoting bike use.