"Blind-eye" knowledge approximates knowledge. Nelson at the battle of Copenhagen made a deliberate decision to place the telescope to his blind eye in order to avoid seeing what he knew he would see if he placed it to his good eye. It is, I think, common ground - and if it is not, it should be - that an imputation of blind-eye knowledge requires an amalgam of suspicion that certain facts may exist and a decision to refrain from taking any step to confirm their existence. Lord Blackburn in(1877) 2 App Cas 616 , 629 distinguished a person who was "honestly blundering and careless" from a person who "refrained from asking questions, not because he was an honest blunderer or a stupid man, but because he thought in his own secret mind - I suspect there is something wrong, and if I ask questions and make farther inquiry, it will no longer be my suspecting it, but my knowing it, and then I shall not be able to recover"
“… Once the Inspector comes to the conclusion that, on the facts which he has discovered, [the appellant] has additional income beyond that which he has so far declared to the Inspector, then the usual presumption of continuity will apply. The situation will be presumed to go on until there is some change in the situation, the onus of proof of which is clearly upon the taxpayer”