On 23/06/2018 20:04, Andy Burns wrote:
Fredxx wrote:

john west wrote:

Does the post office have some way of detecting if a stamp had been
used through royal mail even though there is no visible sign of Frank
Marks?

I thought they used UV spots over the stamp to cancel it.

I have some vague re-collection of that too.


They have used phosphor bands on stamps for at least 4 decades to help
prevent fraud. The royal mail suggests that that they can detect stamps
that have been washed (franking removed) by the degradation in this
phosphor. In this case the stamp hadn't been washed.

Could it have been been the wrong postage amount for the size of the
envelope that resulted in the additional payment rather than the reuse
of a stamp?

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