I wear a sweater (jumper) or a sweater vest 9 out of 10 days between October and April. Wear them with tweed pants, flannels, chinos, jeans, cords, moleskin, just whatever. Sometimes with a jacket, but often not. I had 45 as of this fall and I probably picked up 5-10 more, who knows? I go to a store and say, "no more sweaters!" I buy a sweater.

I've found the same, with MTM and Keydge's which fit like a jumper anyway, a sweater proves a no go.

I find that most homes, restaurants, bars, cars, concert halls, public transport and workplaces are warm enough these days in the winter to be able to dispense with jumpers. But I do think, I v-neck sweater with good tie and shirt can really look the part.

The other issue I have with jumpers is the short life span, mine never seem to last long, before holes start appearing and they fall apart.

Harvie & Hudson call them "sweaters" as well. Anyway - I think sleeveless sweater can be difficult, too nerdy/old-man-ish.

I wear my sweaters around my neck or waist. "Oh Biff... Care for a quick match on the clay? I'll soon be off to fetch my new 1986 Porsche 911."

I have four sport coats that will accommodate a fairly bulky sweater. So sweater (crewneck), jacket, shirt with buttondown collar (no tie), decent pants and shoes, maybe a scarf and hat of some kinds = good casual look. As in going to the movies this afternoon with a girl I am rather keen on.

Naughty.  Just plain NAUGHTY!