In recent years it has been on the 1st of January. I think there may have been some preventative technicality concerning making circulation coins available with a date in the future.
I see London Coins sold this piece below a decade or so ago, concluding it was a doctored piece (is it???) with the H presumably added post-mint. Maybe this is the one Freeman saw and then had second thoughts? Did any forum member buy it, perhaps? Seemed a fair price for such a curio!
Not quite all, though... Eg. the mule 1860 halfpenny listed above as 260A does not appear in the 1986 or subsequent editions, instead there the one given 260A is the missing knot 1*+A, but non-mule, and 260B its proof. Wonder why he never mentioned again such a mule piece? I believe a few are now known?