Sizing of UK-made wool / shetland jumpers / sweaters. Comparisons needed.

Hi, I'm interested in sizing comparisons. I currently have two sweaters from Bosie/Harley in XL and they fit me well, I am tall and with wide shoulders but othwerise slim. A suit jacket would be 42L to 44L, often requiring some taking in around the waist.

I'm interested especially in Genuine Scottish Knits, Skipper's Mill (both of which appear to be from ESK, though I am not sure if the jumpers are the same, they seem to have the same wool but different measurements), and Community Clothing. But info on other brands would be helpful too, such as Malloch's, Anderson & Shepard, etc.