Product - see also detailed description
2nd class blue Machin security stamp Business Sheet with source code MBIL and year code M17L with Security Backing Paper type 2
The 2nd class business sheet was reprinted on 06/03/17 and first appeared used in June 2017, and sheets were found at post offices in July.
This printing has the repeated text ROYAL MAIL on the backing paper beneath the stamps of a new type, with alternate pairs of lines of text inverted.
SG U2961 (also used for earlier years).