Australian Postage Dues - Cto?

There is only one 10d value, Scott J93 (ACSC D155) issued in December, 1959. The back is full gum, with a hinge mark. Is this a Cancelled to order, or was someone just lucky enough to get it pulled off an envelope? (I can't find CTO in the ACSC catalog.)

It does not look like any cancelled to order that I am familiar with. It is a beautiful stamp - is the little black spot over the "O" of postage a plate fault?

Peter

Nope. It is some type of black mark that partially rubbed off, but still there. Could be from the cancellation process.

Guess:
Used as payment for postage due charges, in a bulk requirement situation.

Argument:
CTO cancellations would be expected to be clean precise and somewhat more readable ?

I cannot think of any other circumstance for a cancelled undisturbed gum, stamp.

There is a note in the preface of one of the ACSC catalogs that says that CTO could have been applied as a favor by the post office. I do like Rod's argument, though.

Another argument for Postage Due charges (From a bulk block)
may be the reasonably accurate teeth separation?
Showing some care in the way the stamps have been broken up.

I'd agree with Rod's bulk payment assessment. US postage dues were done this way, though with roller cancels and pens.

There are too many 1953-54 2/- and 5/- dues with nice cancels around, gum or no, to be believed otherwise.

Cancellation likely Cremorne, NSW.

A mail order stamp business (Falcon Stamps IIRC) used the Cremorne PO and received cancelled postage dues as receipts. Many large blocks and sheets exists of most of the values in the no wmk stamps.

Other blocks cancelled Dubbo related to the operations of Seven Seas Stamps.

Cancelled to order stamps were available at any time but can be hard to identify from stamps used in the normal course of postal services but never affixed to postal items.

In the issues after 1931, it can be useful to identify 'Philatelic Counter' postmarks for favour cancels.

It could be as simple as someone asking the PO to cancel this one for me please.