From 17 February 2009 1st and 2nd class Machin Definitives and higher-priced 'make-up' values at 50p and £1 will be produced as self-adhesive stamps with enhanced security features including semi-circular slits and an irridescent overprint. Later Royal Mail announced that the values over £1 would also be issued in this format.
SG Catalogue/Norvic cross-reference table -click here. See other blog entries for the history of the development of security Machins.
This is a date block of 8 of the first reprint since 2009 - 30/08/11 - and has the M11L code.