We probably need a new menswear vocabulary to describe the odd jacket's place in the wardrobe. The English have traditionally thought of it as casual, but that hardly seems accurate in a time when casual describes something considerably less dressy more often than not. Nor, on the other hand, is an odd jacket up to the same level of formality as a suit irrespective of the millions of young women who can or do not differentiate one from the other.
Useful as a new term or terms might be, we are here today to speak of gray once again, and gray it shall be. Or rather, gray complemented by olive green in a "casual" combination that is one of my personal favorites.
I have written over and over again that light blue shirts are great with navy but less so with gray. What works better are pinks, and tans like that of the shirt in the photo. Gray and tan in turn are well matched to olive and bottle green, shown here in my country-appropriate striped silk jacquard necktie whose navy and olive bar stripes and gold pin stripes are colored similarly to the green, gold and blue medallion print wool and silk pocket square. Striped neckties are in my opinion a little too casual to wear with most suits, coming into their own with odd jackets of all flavors. But there is that casual word again. We need another term.