21 April 2016 - 90th Birthday of Her Majesty Queen Elizabeth II
In addition to a set of 6 stamps and a miniature sheet, Royal Mail also issued a retail booklet and a prestige stamp booklet. The definitive pane from the PSB includes 2 pairs of 1st class Machin and one each of the 1st class country definitives.
Pair of Machin definitive stamps from prestige stamp booklet, ordinary gum
1st class purple - O16R - REIGP - Norvic 3748
1st class red - M16L - MPIL - Norvic 3702P.6