It was cool the other day, but not to the point of requiring a topcoat, and that called for a paisley silk scarf. When a man is wearing flannel trousers and a tweed jacket as I was, most of him stays warm enough until temperatures fall below 50 degrees (10 Celcius). The exception to this is of course the vee of his jacket opening, where only the cotton of his shirt may protect him from the elements. That is where either a waistcoat, sleeveless sweater or scarf comes in handy. Of those I prefer a scarf.
Easier to remove when entering heated rooms, the scarf, that precursor of the necktie, may as you know be made for warmth from wool, cashmere, angora and blends thereof. The best looking of them in their odd jacket complementing context are however silk printed with dots or paislies, which by the way is nearly as warm as its woolen relations. Tied in a loose four in hand with the front blade thrown over the knot, they give something of the look of an extravagant necktie to the day's clothing (remember, we are pairing silk with tweed in this context and not business worsteds where a more conservative solid cashmere may be a better pairing with navy pinstripes).
The best silk scarves today are made from heavy printed silk which is either pressed into a tube, so that the printed side is always visible, or backed with cashmere for extra warmth. They can be pin fringed, meaning there is half an inch of light thread at each end, or hand fringed with three inches of knotted silk. The latter is a richer look, in keeping with the sporting textures and colors of tweed.
The scarf wardrobe need not have as diverse an assortment as the neckties in a man's closet, but there ought to be a reasonable amount of variety. Perhaps two solid cashmeres for the office, white for evening, and a pattern or two for less formal occasions. If at least one of the latter can be a richly colored silk, all the better.