Quote:
It's a DEPOSIT DUTY EXCESS custom house marking commonly found on imperf $1 stamps.
But not SOLELY imperforate stamps (for the benefit of the non-revenue collectors here). While it might be a positive indicator, it is not in and of itself a determining factor. This cancel is also found on perforated stamps (I just received a very complete strike on a pair of 25c Entry of Goods perforated).
You see this cancel frequently on the 50c part perfs as well.