Date (happened)
before 1966
(possible)
qualifying source passages 547010; telling lecture nids 1857
Told / reported
1966
passage 547010 (lecture nid 1857, 'Nevilles Thoughts If Leaving Permanently'), delivery claim 1966 exact/certain (Neville explicitly says 'this world, 1966')
Neville describes his own physical symptoms when he goes into the Silence - parched hands and mouth, an effect like a diuretic - and offers them only so listeners are not disturbed if they have them.