April 2015 - 2p green Machin definitive from counter sheet reprinted in 2016.
Year code M16L, source code MAIL. Printed 12/01/16, and again 03/02/16
SG U2921 (as used for previous years)
cylinder block of 6, or
date block of 10 - 03/02/16, 05/07/16, 21/12/16