It's interesting isn't it, that the Royal Mint's view of the overdate being 8/2, predates this article by about 4 years. Given Bamford's scepticism about the 8 being over any figures other than a 3 or a 6, it either suggests complete dismissal of the RM conclusion on his part, or an unawareness of it. My money's on the latter, as surely he would have referred to it in the article, had he known.
He does indicate that the 3 used in the 1853 dies was the wrong type of 3 for the redundant 1853 dies to have been used for overdating in 1858. So maybe he thought that the 1853 dies would have been already disposed of in 1858, and therefore not available for use anyway.
As a footnote, since the 1858/6 is always over a small date, the RM must surely have used the 1856 small date die. They obviously kept that.