I am guessing that this was not the first time such a break had happened. Presumably the problem led to the strengthening of this part of the camshaft in subsequent years.
36 4G, 37 VH, 54 KH(A), 75 Healey 1000/4, 52/53 ex ISDT KHA (project).
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.