I am exploring the scope of used copies of the 1 cent on 2 cent, and 2 cent on 5 cent strips of ten of the 1915-16 surcharges, Scott 153, 154, O87 & O88, as well as the less common 155, 156, O90 & O91. Used copies of this group are not very common, and legible dates are even tougher to find. But a recent acquisition that has piqued my curiosity is single copy of 154p with a Harper cancel (thanks, Martin). I am curious to find out if anyone has a used copy of any of these surcharges with other than a Monrovia cancel. Just because I like it, I have also attached a scan of an interesting cover of this issue containing pairs of the scarcer 156 & O91.