Cape Of Good Hope Half Penny Grey/Black With A 1d. Handwritten Red 'Overprint'?

Can anyone offer any information or advice about this stamp?

It's a Cape of Good Hope half penny grey/black with a 1d. handwritten red 'overprint'. Perf 14. There's no outer frame line but I can't see a watermark due to the paper on the back so it's either SG28 (1871-76), SG40 (1882-83) or SG48 (1884-90).

It has a Barred Oval Numerator Cancellation which runs horizontally. David Mordant's 'The Barred Oval Numeral Cancellers of the Cape of Good Hope from 1863 – 1963' shows this to be quite unusual, and of the two horizontal possibilities it would appear to match the one with the smaller numbers and rectanglar centre; 6c1, Jurgens Type 58 (2.5.2). The only cancellation to fit this description in Mordant's work is No. 227, and the numbers on the cancellation would appear to fit that, showing it to be cancelled at Kimberley.

It's obviously not a forgery of the famous Griqualand West SG1, because it's not on a 4d. stamp. But could it be from Griqualand West? Does anyone have one like this?

Couple of images attached.

I do not come across this type of overprint in the SG catalogue.

I do see a somewhat similar overprint on another stamp for this design that is marked as a forgery. I think "fake" would better decribe that.

The line that obliterates halfpenny has all the indication of being handwritten. That, very much, is a red flag.

I think it is one of two things ,first used as a revenue stamp and second some local provisional, unauthorized usage . I don't have any reference that can help .

I don't think a forger would waste time on a so damaged stamp .

A professional forger wouldn't, but someone amusing themselves with a damaged stamp might.

The postal fiscals are listed. It isn't that. Local provisionals, such as Mafeking, are listed as well.

It has all the markings of a fake. And who knows whether the damage occurred before the overwriting.

Here is the original 1874 Griqualand West #1 ,from the A.P.S. files ,they also have a few fake copies of various inks . So it could be a forger's "practice copy "

Robson Lowe makes no mention of this (that I spotted) in the Encyclopedia.

I infer from his notes that Kimberley used a cancel numbered "1" until 1880. The shortage of 1d stamps was dated to September 1874.

The original postmaster manuscript surcharges dating from 1874 don't have a "1" with a serif. It's unlikely that the postmaster would use dramatically different handwriting.

If it was arising from a later shortage, and if that's a Kimberley cancel, would the underlying stamp not need the "G"?

And, of course, if genuine, the cancel needs to be on top of the surcharge. You might be able to use a magnifying glass to see if you can confirm that the surcharge is actually on top of the cancel.

Feel free to pick at any flaws in my logic.

Thanks everyone, will take another look later today hopefully

Had to have another look.
Even with my son's digital microscope I can't work out if the cancellation is on top of the red ink, or vice versa, it just looks darker! It did help confirm it says 227 though. I've tried to photograph the microscope screen and attach a pic but it's hard to get the detail sharp. What you can see is where the 7 from 227 is under or over the '1'.
Interestingly SG and Scott do show two different styles of handwriting for the overprint... although still no serif.
Anyone ever sent anything like this off to SG or similar?

SG does not certify anything.

They may list constant varieties that were unknown. In this case, however, it seems that a script 1d on a (different, 1/2 d) Cape stamp would result in speculation it might be an as yet unknown provisional stamp.

Chances are they will ask you for some supporting evidence there should be reason to think it could be an undiscovered provisional.