Christmas Madonnas - how many printings?

The Christmas Madonna stamps introduced in 2007 were "produced in reaction to a popular demand for stamps bearing an overtly Christian image" - this despite the fact that the main design for Christmas 2007 was Angels.

And each year since, these stamps have been reissued, with Royal Mail Philatelic telling us that "they are the same stamps as were issued in 2007."  But how many stamps can be printed from one set of cylinders, and how many did they stockpile originally?  We now know that there were reprints in 2008 and 2010 - does anybody have any other printing dates?

 
A close examination of the three lots that we have shows no appreciable variation, although colour mis-registration does produce slight differences.

Dates reported:

1st
- 15/05/08 - Tallents House Dec 11
- 02/06/09 - Cambridge Nov 10, Enfield
- 08/08/10 - Dereham, Cambridge, Enfield Dec 11

2nd
- 19/05/08 - Tallents House Dec 11
- 18/05/09 - Enfield
- 24/07/10 - Enfield
- 26/07/10 - Cambridge Nov 10, Dereham, Cambridge Dec 11

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