On the 21st June 2016 royal Mail will issue the next prestige stamp book, entitled The Great War. The bad or good news (whichever way you look at it) for Machin collectors is, it will not contain a mixed Machin pane.
The mixed usual definitive pane will be made up of 4 x 1st class stamps from the four regions of the UK. England, Northern Ireland, Wales and Scotland or if you prefer UK country stamps
Four 1st class poppy stamps and a central label will make up the rest of the pane.
Douglas Mayall reminds me these are not definitives.
Thanks Douglas for your e-mail.
"There are three flag stamps for three countries, only the Fields stamp for Northern Ireland is a definitive"