Slogan Self adhesive Machins

1974 Produced rather to poke fun of the Post Office, these series 4 pair of Machin Self Adhesive stamps went too far. The PO were not amused, and deemed the slogan must appear on the left half of mail, or be detatched, hence the overprint by hand. In fact so unamused were the PO, just about then the PO ceased the stationery office imprinting stamps on personal items. The ever devious stamp dealers then used existing stationery envelopes, pre stamped, and printed on the left-hand half, thus producing private miniature sheets.