1889 8c PSC for overseas mail. This unused item has the error of "inverted 8" at the NW and SW corners. It is not rare but more difficult to find in used condition. This card also exists with surcharges due to changes in postage rates. To date there is possibly only one example of the surcharged card with the error recorded, on a card surcharged 4c.
Well, here is the used "inverted 8" card that I managed to obtain at the auction of the Sarawak Society AGM over the weekend. It is plainly philatelic without a message. It was posted in Sandakan on 21 MY 1894 and arrived at The Haque in Holland on 29 JUN 94.
An overpaid used item addressed locally. There is no message at the back. Mansfield, Bogaardt & Co was an Anglo-Dutch shipping company with an office in Sandakan. Someone in the company was evidently a collector.
A philatelic item bearing a 19 bar cancellation. This "eye shaped" cancel is different from the one illustrated in Proud's book in being significantly wider. The card also has a Sandakan D4 in red with a partial dotted circle.
There is a transit cancellation for Singapore at the back and an arrival postmark for Erfurt in Germany addressed to a well known stamp dealer of the time.
It took 7 days to get to Singapore and then arrived in Germany just over 2 weeks later, probably a bit faster than sea mail nowadays.