For anyone who worked for the NCB in the years following the catastrophe, the words "bungling ineptitude" were burnt into the psyche. The chairman at that time, Lord Robens (at one time a minister in a Labour government, but appointed to the NCB job by a Tory government) put in his resignation. And by all accounts, he expected to go. Theoretically, and in accordance with British custom and practice of the time (but noticeably abandoned in recent years) he had ultimate reponsibility for Aberfan.

But the unions all protested; the government made clear that Robens retained their confidence; the Tories (by then in opposition) supported him and his resignation was rejected.

Thanks Jeanie for the additional info. I would have been surprised if the account at the top of the thread had been the full story, but I must admit I've not followed up any of the various links provided.