I got this several years ago, and it now seems there is an increased interest in such. The coin has a lovely appearance with a sheen of lustre that sadly can really only be seen in hand (I believe it is much more likely that the original flan was a penny and not halfpenny as NGC designated):
Yeah, a halfpenny would be too small I think. I was going to say weigh it but since it's slabbed that's not do able. Even without the sheen it's a lovely coin, 7Jags. Thanks for showing it to us. Bruce
This is probably the only one they have seen and they got it wrong. A Penny weighs 9.45 grams so maybe their scales were wrong too.
If the halfpenny and penny planchet are a different size you might be able to get a rough measurement through the slab. Bruce
Believe it was 1966 but will check later on today. I suppose the flan could have been mixed in after security "railroad track" edge applied.