Just ran across this old thread. Examining the sample more carefully, it contains 9th series stickers and checklist, but it contains the 11th series wrapper, and also has the 11th series product code "478" at the top. I'm now thinking this was really a sample made up for the 11th series, and 9th series stuff pulled from packs was used because the 11ths hadn't yet been printed. 10ths probably hadn't been printed yet either.
Come to think of it, the yellow wrapper pictured may not even be an 11th series wrapper. It could be the yellow wrapper was planned, and an old yellow wrapper from the earlier run was used for that reason.