Further to RetiredBA/BY's post, the other statements he correctly mentions (pins, unsafe seat not identified) were taken from MoD reports.
Bob, I do not doubt that the pilots you taught were attentive and took ejection seat safety seriously. But some very senior officers (and Civilians) demonstrably did not. See dctyke's post, above. If the regulations and instructions had been followed, this accident would not have happened. Who withdrew the wherewithal to satisfy those regulations and instructions? Again, dctyke nails it. What does the risk register (or hazard log, or impact assessment, or Safety Case) say about the decision to withdraw that capability? A rhetorical question - there was no Safety Case. Again, as admitted by MoD. Been there before.