Great Britain 2 Pence Scott 15 Or 19?

Hi

Came across this poorly centered and trimmed 2 Pence Blue. Perf 16. Trying to determine whether it is a Scott 15 or 19. Scott distinguishes between the two by paper type and thickness of paper. Bluish paper is problematic with US stamps as the paper isn't actually blue. Don't know if the same applies to stamps of Great Britain. Watermark listed in Scott as #20. Hoping the images are useful for opinions:

This is white paper, so it's #19. Examine these engraved stamps from the back to get a better determination of blued paper (SG term) which is indeed blue color. Of course, blued paper has been forged, usually badly. The perfs tips or imperf edges soak up more ink with a heavier blue showing there.

hy-brasil

Thank you. This is the only one I have of this type. Haven't seen any others up close for comparison. Happy to hear blued paper is actually blue with this issue. Makes identification much easier. US bluish paper is gray I've heard. Haven't seen any of those up close either. If I own one of them they remain unidentified.