The description at the top must have been by a British person, because it describes what in the US we just called a pullover sweater vest. I know in the UK a "vest" is what Americans call a tank top, basically a pullover knit shirt with armholes cut in deep and neck opening scooped down low to form narrow straps over the shoulders, like an old-fashioned tank swimsuit. The white ones traditionally worn as undershirts have been referred to as "wife beaters" in the US since the 90s. Anyway, tank tops in the US sense were very popular for men in the 70s. I had several, even though I was so skinny that I looked terrible in them. Many were rib knit. I had one in yellow with rainbow topstitching, one in denim-look blue with a slight tie-dye effect, and one in brick red. Wore them with the cutoff jean shorts that were everywhere at the time or with the standard flared or belled jeans.