Information On The 'Postal Commemorative Society'

Evening, All,

I've recently inherited my grandfather's stamp collection, and he has roughly twenty-five commemorative panes from an organization called the 'Postal Commemorative Society. Each page has a MNH block of four starting with the 1783-86 'Endangered Flora' set and random sets through to the #1940 'Toy Teddy Bear and Sleigh'. At the top half of each page is an illustration complementing (but not duplicating) the stamp's theme.

Does anyone have any knowledge of this organization, and if they are still in existence today? The cover letter welcomed my grandfather into the society, and said after 1979, membership would be closed forever. Sounds like a sales pitch, but you never know...

Thanks in advance!

Cardinal Bass.