I grew up there, I saw what was actually happening.
Growing up in England, where sweaters were called "jumpers" or "pullovers" if they did not have a front opening, there were several specific styles. Two of the most popular came from the Channel Islands, the island of Jersey (very plain) and the island of Guernsey (slightly more ornate). They were also distinguished by the style of the collar, shoulder and wrists. Back in those days, sweaters were knit on needles English sizes #12 and #13, American sizes #1 and #3.
Names were shortened, so a child might be told "put on your Jersey", or "put on your Guernsey". If it didn't matter which, it was "put on your jumper". "Gansey" was a child-level nickname.
Came the end of WWII and, following right on, the influx of American tourists, who at that point were the only people on the planet who had real money to spend. Most of Europe was bankrupt or nearly so, and desperate to earn dollars. Therefore, if some of these untutored American tourists asked for a "gansey", that is what was sold to them, with a politely straight face and no corrections.
The rest of us wore what was available, and the post-war depression lasted until the mid-1950s (which was where I came in). Growing children wore striped sweaters. Why? Because the old ones were unravelled and re-knit into a larger size, with whatever color wool was available. During and after the war, new British wool was virtually unavailable, and most of it was reserved for export. I am told that during WWII many women even took their knitting to the movies with them, as no-one had time to just sit. Children had to be clothed. Socks had to be worn. My mother did not knit, she sewed, so others made my sweaters and mother sewed clothes for them in return. I grew up watching my female relatives knitting socks and sweaters all the time - embroidery was "fancy-work", to be indulged in during idle hours or while visiting one another - unless, that is, it was for the church bazaar, in which case it took precedence over socks until the bazaar was over. Woe betide the child who wore a hole in a heel durng this period.
I only ever saw a knitting sheath in a museum. By the time I entered this world, knitting machines had taken over most of the work formerly done that way.
Olwyn Mary in New Orleans.