Another clue:
Somebody thought it important enough to design quite a detailed work. Someone thought it significant enough to make this tapestry.
Have the crown and the date and the stylised English roses given it away? (extra clue: Charles and Diana were married in 1981... did you spot their initials at the top of the design?)
I think the red/white/blue item at the bottom of the design is intended to be a cradle. There's a lot of fecund/flourishing greenery.
You must be close to guessing, or have already guessed, that this records the birth date of Prince William.
It's done in wool on tapestry canvas - as a tapestry or needlepoint, depending on your terminology. The cream areas are unstitched, so you can see through them to the backing board.
If you know any more about this design - where/if it was published, who designed it, if it was available as a kit - please do leave a comment. It could have been a charted design (thus able to be used for cross stitch or canvas tapestry stitching) or a kit. I incline towards the charted design (maybe in a magazine) because most tapestry kits of this vintage and up to the present day generally include enough tapestry wool to stitch the background, whereas counted cross stitch on Aida cloth/linen/evenweave doesn't usually involve stitching the background. This stitcher chose to interpret the chart using wool and tapestry canvas, rather than as counted cross stich. There are earlier designs from the 1930s and 1950s employing tapestry canvas with the background left unfilled/holey, but it's rare for more recent work, in my opinion.
