“I can see no reason for saying that a discovery of undercharge can only arise where a new fact has been discovered. The words are apt to include any case in which for any reason it newly appears that the taxpayer has been undercharged ...”
“The discovery procedure in s 29 has its origin in earlier tax statutes and may apply where, after normal finality of an assessment, some new fact comes to light or incorrect application of the law ... or where, for any reason, it newly appears that the taxpayer has been undercharged ...”