1st class red Security Machin forgery.
One of several types which have been produced.
Coded M13L MTIL these have a dull background, very clear lettering except that the 3 of M13L seems closed at the top the stamps show red under UV lamp.
The phosphor does not react to UV light
NB Some of these forgeries are difficult to distinguish from each other, and I may have listed as different stamps which are in fact the same type as identified by the Modern British Philatelic Circle or others. If this proves to be the case and you wish to return a purchase, please email first per our Terms and Conditions, so that we can discuss.