That looks like a pretty adaptable tweed, Cuttingboard. You could go simple with medium or dark gray flannel trousers, a blue shirt with a small pattern (micro-houndstooth, mini-tattersall, graph paper check, etc.), and matte tie in grenadine (as Beatlegeuse suggested), wool, cashmere, or even a twill silk as long as it wasn't too shiny. A nice, muted silk square in a moghul pattern or similar would also go nicely.