Wikipedia says "A knickerbocker glory is an ice cream sundae that is served in a large tall glass, particularly in the United Kingdom."
But the knickerbocker is a pair of knee-length trousers for children, particularly boys, and those engaged in outdoor activities such as sports, golf, baseball, cycling etc.
But the knickerbocker didn't go away, it just got crazier and was an essential item in any self respecting culotte wearing 70's fashionista. I remember having a pair myself in the 80's too, so one has to respect their short stature as a trouser but longevity in wearabilty.
Until finally it has been revived from the sartorial back of the
wardrobe by me and the moshi elves.
And there will be a little shop update on Sunday this weekend. Keep your eyes peeled for times which I will confirm soon.