I seen them posted on this forum, but never in hand. That is why I would assume they came from English vault. There is up to 150k of the 1912 $5 remaining, so not hard to imagine the BOE had a nice round number in their vault, eg 10k oz gold. A $10 1912 would be nice to find.
Have not updated in a while, but some numbers on mintage.

Have not updated in a while, but some numbers on mintage.
























