This type of display item first appeared in 1967 and the numbering system, when used ,follows the sequence of the counter grille cards.
The exact use of these items remains unclear. They were available for display at the Post Office Philatelic counters around the country with the Edinburgh Philatelic Counter address printed across the bottom.
There were two variants done for the US and German agents with their relevant address across the bottom. They may well have been distributed to dealers overseas and had an important role in the British Government's desire to promote trade and cutlural links around the World through Embassies and Trade Delegations.
The initial items had the stamps affixed and were sent out pre-release on occassions. This seem to cause some problems with the German items as stamps were been returned to the UK for usage pre-release date. The stamps were therefore "cancelled" by various sized handstamps. This solved the problem but created an eagerly sought after over-print for collectors. By 1970 the stamps were de-faced with a biro or felt tip pen across the corner. The US agent's items always appear with the stamps un-cancelled or un-penned.
At the London Stamp Show 2000 variants of the 1969 Gandhi stamps were being sold. The paper was of modern origin and very white, the printing looked to be done on an ink-jet printer, the PL(P) reference number was for a 1973 issue. I do not believe them to be original items !
If you are unsure about an item , please feel free to ask as there are other ways to recognise a copy . For obvious reasons I am not going to list them all here.
Please note , I have not indicated the size of the pages. Some exist wider than A4 with four holes punched. Others exist as a slightly oversized A4 display item. Collectors have often trimmed the wider items down the left side to make them more presentable. It is normally possible to see if this has happpened by looking carefully along this border for signs of recent cutting or an uneven side.