From 17 February 2009 1st and 2nd class Machin Definitives and higher-priced 'make-up' values at 50p and £1 were produced as self-adhesive stamps with enhanced security features including semi-circular slits and an iridescent overprint.
These initiatives are part of the on-going development of security features for Stamps. The slits are designed to inhibit the removal of these Stamps for fraudulent sale and re-use. The overprint features the words 'Royal Mail' in a pattern reminiscent of security features on banknotes.
Royal Mail announced that the booklet stamps printed by Walsall Security Print would be issued - or available - from 31 March, but the Design Classics Retail booklet issued 10 March 2009 also contains the new stamps. However these are not the same as the later issued regular booklet stamps, as these have the security overprint ROYAL MCIL indicating that they are from Custom or Commemorative booklets. These can only exist in blocks of 4, coming from booklets with two special stamps, one on each side of the booklet.
From the following booklets:
Design Classics Bus+phone, Mini-car, Concorde, Mini-skirt and