Just to be a bit left field on this one ( I do have the usual army jumpers too). You can now find a lot of unissued British police jumpers (In Black) online at the moment. They even do fat sizes. They are mid weight and 100% Wool. They look surprisingly smart and comfortable too. The only drawback with them is (as I have found) that they snag easily because it is not a tight weave.
Hand knit Aran, Guernsays or Icelandic style Lopi ones
Brilliant kit; warm, breathable, hard wearing and very comfortable.
I've just tidied up an Aran that I knitted twenty years ago for HWMBLT and it's still sound, still his favourite jumper. It's blue and over the years the colour has mellowed and softened so much that when I found the little ball I kept for darning to repair a snagged cuff I had to bleach the colour our a bit to make it match It still looks good
Lopi knits up very quickly indeed, it's not complicated and not beyond any man to manage to do his own
Army jumper. Best bit of clothing the Army have ever had. Was recently phased out, but the manufacturers have just received another MOD order for a new production run so they must be coming back. They are very popular with the SFSG who are allowed to wear them. Old school is considered very ally!
I have a Norwegian Army jumper, though I tend to wear fleeces now. I have a knitted cable stich jumper in the loft, but the best I've ever had was a Falkland Island jumper, tried to get another a couple of years ago, got the sellers details from Falkland House but they never replied.
Made by Norlender of Norway. Really thick oiled wool, were available in navy, green or oatmeal. Had a swift look online - not sure if the make it without the pattern these days, did however find this foreign page with better pictures near the bottom. LINK Very cosy though mine was big before loosing 12 odd stone so have to dig it out and shrink it.
Sorry can't tell you where to get one - my google-fu is weak today.
Army wooly pully. There's a company called http://www.outdoorknitwear.com/store/category.php?category=17 that do them for under forty quid in a whole load of colours incl non military ones.
I chuckled at the surprise that the ex police jumpers also came in fat boy sizes... (I put my old Kent one on a while ago... Quite snug)