Collectors will recall that the security stamps were originally issued in 2009 with no specific year code - the word MAIL appearing where later there was a numeric code. Whilst most of the NVI stamps - 2nd, 1st, 2nd Large, 1st Large - were subsequently reprinted every year with relevant year codes, the Signed For pair only occurred with MA10 codes, and the £1 ruby didn't appear until 2011 (M11L). The £2 arrived in 2013 (MA13) - but for the others we will only know if they were even printed when actual examples are found.
But a recent discovery suggests that the 50p light grey (replaced this year with the slate-grey version) won't be included - because a printing of 07/08/09 has now made an appearance. If it has taken that long to use the original printings of 08/12/08 and 18/03/09, it seems unlikely that there were more printings in 2010 and subsequent years.
In certain light there appear to be slight differences in the shade between the 18/03/09 and 07/08/09 printings:
The only difference I can see is that the bottom margin is deeper on the later printing, but this may not be a constant variation.
Jim has sent this comparative picture of the 18/03/09 printing with the earlier 08/12/08 printing. As you can see the later one is much darker.
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