Togo Yacht Purple Overprint

I recenly acquired attached German colonies Togo yacht stamp, British occupation, with inverted overprint. So far in Stanley Gibbons and Scott (I do not have the Michel) I always see all overprints in black, are there other known stamps with purple overprint or is this a fake by default because of the deviating color? It does have an expertise marking on the back.

Forgery

Aside from color, the genuine were printed by typography; this is undoubtedly rubberstamped. In any case, the letterforms/font is wrong.

May we see the back, please?

The postmark is wrong for an overprinted stamp, too, is it not?

It's correct for the period, I believe. British and French authorities used abandoned German cancelling devices for about a couple of years before new ones were made in British and French colonial styles. German colonies references (Friedemann for one) give only the last date of use by German postal authorities (Anecho's last listed as August 6, 1914 with the office noted as being lost the same day), not the entire lifetime of the devices.

Thanks for the info.

mhendrickx, with good magnification you can often verify that the overprint is on top of the postmark.