I make these wall calendars every year with one big image in the background or twelve themed images in alternating squares.
I note the birthdays of friends and relatives (and cats) with their name on the date plus a bright gold star behind it.
This image was the cover illustration for Issue #4 of the science fiction publication New Worlds Quarterly, from June 7, 1972 (see second image, below calendar). New Worlds Quarterly is a venerable British magazine which has been published, in some incarnation and under several different names, from 1936 until the present day.