Thanks Jon, not e bay, no...............oh well, as you've asked, I might as well tell the back story on this one, which is a bit circuitous. You might remember that during December 2018, a forum member posted his collection of 20th century coins. The thread is here. As suggested by Gary, the collection was indeed, at some subsequent point, left with Colin Cooke to dispose of - a fact confirmed to me by another forum member a few months back - and for a long time just seemed to be sitting there. There were several pennies I was directly interested in, including the aforesaid 164A, so I contacted Lee Brownson and asked if there was likely to be an auction of them anytime soon. Lee replied to say that there was not enough value in the collection for an auction, but if I let him know which coins I was interested in, together with a suggested price, he'd see what he could do. So I e mailed details of the four specimens I was interested in, and Lee replied to say that it might be a couple of weeks or so before things were sorted, but he'd taken a note, and would get back to me.
Towards the end of July, I received an e mail from Lee to say that Gary's entire collection had been sold to a single buyer, but Lee had held back the 164A for me. Buyer wanted the others I'd requested. That's how I got it.
I hope I'm not speaking out of turn here, but I can't imagine it's a state secret. I've certainly not been asked not to say how I came by the coin.