14 May 2015 - Machin definitives from World War I Centenary PSB on First Day Cover
The 2015 WWI Centenary stamp issue includes a prestige stamp book containing 7 special stamps and a pane of 8 stamps. These are 6 x Machin definitives - 2 each 1p, 5p & £1.33, and a pair of Poppy stamps
The set of 3 stamps on Royal Mail Great War 1915 first day cover with the Europhilex London Great War 1915 First Day of Issue postmark.
Stanley Gibbons numbers not yet known for the £1.33, but U3010 and U3012 for the 1p and 5p, which have already been used for prior years' stamps.
Full details of this stamp issue - http://www.norphil.co.uk/2015/05c-Great_war_1915.htm