You may be right. For about 2 years prior to decimalisation and during the changeover period, I worked in my father's grocery shop and persuaded him to order some £10 of pennies every week. I duly went through all these, and do you know what I found? Virtually nothing. No KNs, no 1950-53 pennies, no MEs, nothing. The KNs are most significant as I don't believe they were ever that rare, the inference being that they had all been withdrawn from circulation by collectors. 12Hs were quite common and 18 and 19Hs would come in from time to time, but no more than half a dozen each during the whole period - and usually horrid. So yes, I think the rarer coins have survived in disproportionally high numbers. I do not however agree with your assertion that 1967 pennies could ever be sought after in any shape or form! Yes perhaps 1967 was not the best example to make my point but trying fill the Elizabeth II gaps is not easy as most dealers don't bother to deal with them. Too new at decimalisation, even given that tonnes were probably tucked away it must still be insignificant compared to the amount melted.