Barbados Britannia Imperforated With Watermark

When sorting a Barbados Britannia collection I came upon this stamp, it is imperforated and looks quite common, but the peculiar thing is that this stamp seems to have a star watermark (see backside midbottom). Scott only mentions existence of this stamp in an unused pair. SG does not mention this variation at all. I'm thinking of having this stamp expertised, but first wanted to check in this forum if there are any other ideas.

It could just be a perfed stamp trimmed also.Off center stamps are not uncommon with these issues.Lot's of petty trickery in early Barbados… An example of a stamp off center.

With stamp in hand, you might look closer at these areas; try lining them up with an existing stamp perfs and see if the are aligned.


Don

The 4 dots on the left side where the arrows are align to perf 15. Also on the right side below (next to the purple marking) I see two dots that align to 15. So would that suggest that it is an offline pinperf (heavily offline both at the right and at the bottom), that has been trimmed just inside the perflines?

It can't be a pin perf because they have no watermarks.That leaves SG 44 1870 rough perfs 14 to 16.The shade is identical.