This is the closest pattern I could find on Ravelry for it. The pattern is a leaflet from Sirda for the yarn Snuggly Smiley Stripes DK. (but I used a different yarn!)
AND, I really love the Knitcol yarn - the stripes are brilliant!

The size of the finished vest turned out to be a size smaller! - I knitted a size 2 but it’s turned out a size 1 - I’m not a tight knitter, so just be aware of this!