Well, one thing is for sure; the installation doesn’t comply with current good industry practice. Is this OK? The fact is that it is the School’s decision as to whether it is or not. They can’t expect safety kit to last forever, so renewal should at least be considered (and if the risk is assessed and it’s reasonably practicable to do it, then it must be done – “we can’t afford it” is no protection from that legal requirement).
At the very least, they know about it now, so they must review their fire risk assessment to determine whether it’s acceptable. They could use the guidance in the Fire Safety Order Guide on ‘Fire Safety Risk Assessment - Educational Premises’ – if they conclude that the system provides all the F, D&A functionality recommended in Parts 1 and 2 of the Guide, then it might be that then can make a case that it is acceptably safe?
All the above assumes that the system is in ‘steady-state’ maintenance – if they modify it then that would make the case for retaining the non-compliant system weaker.
Finally – this is a school; the biggest risk tend to be arson and the most likely outcome is significant property loss or damage. There might be a case for renewal due to the enhanced asset protection that a compliant system might offer?