The one and only green triangle

I seem to have known this Christmas decoration all my life, though it probably appeared some time in the 1960s ( unlike myself, who appeared in the ... gulp ...1940s ).
Our daughter really has known it all her life though, and one day it will pass to her, so when she puts it up Christmas will really have started.
I think I'll delay for a few days though, the house needs tidying just a little first ...