I've written many times before that the breast pocket on the left hand side of a man's jacket should always be filled with a pocket square. And when the textured, colorful look of tweed jacketing calls for a more sophisticated visual than can be provided by simple white linen, it's time for silk, particularly paisley silk like the one from Drake's London in the photo.
The kidney-shaped paisley is one of the world's familiar patterns. It originated in Persia, but its western name is taken from the Scottish town of Paisley which became the best-known producer of the design in the early 19th century. That may be because the inhabitants of Paisley did the best job of complementing tweed, the standard outerwear of the area. They definitely are credited with printing five color patterns at a time when the competition made do with two, and that's a good start.
Personally, I think that multi-colored paisley makes the best silk squares. The complex designs let a man look refined and easy going about his dress at the same time, with squares that have grounds that relate to nothing else that he's wearing and multi-colored patterns that may complement shirt, necktie, jacket or all three.
I wrote earlier this week about madder and tartan, two neckties that also complement tweed. Add a paisley square to either one, and enjoy.