Even before the advent of the popularity of Scouts on Stamps, the Mafeking Capes (Scotts #178-180) were prized items to British Colony collectors. The counterfeiters were at work on these three stamps even when the prices were between $5 and $15 apiece, and when Scott's catalogue had them completely undervalued. In those days, the sale of a nice forgery was well worth the effort. All three of these photographic print stamps have been victims of forgery, perhaps more easily done than with printed stamps.
The forgeries, however, are almost always perforated more nearly 11 1/2 or 12 1/2 than the 12 that they should be. Moreover most of the fakes have fictitious postmarks as well, and this factor helps greatly in detecting them. The phony cancellations are always very clearly impressed and usually bear the date AP (April) 23, 1900. The forged postmark appears to be genuine, namely a single circle mark of 25mm diameter; however, if the top of the word "MAFEKING" and the bottoms of the letters "C.G.H." are more than 1/2mm inside the circle, then you are most assuredly stuck with a fake.
The majority of the real cancels are impressed centrally on each stamp, so cancelled singles "off cover" will have most of the mark visible. A partial postmark should, therefore be subject to suspicion but not definite proof of falsity. One more detection method is available. The consensus has it that No. 178 was issued on April 7, 1900 and the other two on April 10. The besieged defenders were relieved on May 18, 1900 and, therefore, the last use of the stamps was made on May 17. Cancellations in February, March, early April and after May 17 will thus be forgeries.
One philatelic source states that forgeries exisit mainly on cancellations from Capetown and Kimberly. Nevertheless, it is clear that not only do forged stamps with phony cancels exist, but also fictitious cancels on genuine stamps. This latter possibility was probably encouraged at a time when postally used examples commanded a higher price than mints. Now, however, mint copies are catalogued at substantial premiums, although this price differential would appear quite unwarranted, especially as to the eagerly sought after No. 180.