A man needs more than one overcoat, assuming he lives in a climate that requires coats to begin with, and it is time to begin thinking of one should you be in need. A first coat should usually be a tan or khaki raincoat with a zip-out lining, and the second something to wear to and from the office, such as a herringbone or a guard's coat in dark brown, mid-gray or navy blue. And if there is a third, that might well be a Chesterfield in charcoal gray or midnight blue (either color is fine so long as it is different from coat #2).
Invented in the mid 19th century by George Stanhope, 6th Earl of Chesterfield (it was the 4th of that line who wrote the famous Letters to His Son on the Art of Becoming a Man of the World and a Gentleman), the popularity of the Chesterfield rose in parallel with the spread of the lounge suit. Replacing as it did the frock and other body coats, it has a relative lack of waist suppresion in the classic cut and a made to measure or ready to wear (if you can find one) Chesterfield is nearly indistinguishable from its bespoke cousins, which makes it a good value as well as good looking.
That is not the only positive to the Chesterfield of course. A plain or herringbone Chesterfield is the most appropriate thing to wear on solemn cold weather occasions and in the evening, and also does double duty as day wear in a city whether or not one is called upon to walk with the most famous actress of her generation.
Typically a three button fly fronted single breasted, the Chesterfield may or may not have a black velvet collar (those had a practical advantage before men washed their hair - when the collar got dirty only the velvet needed replacing) and can sport either notch or peak lapels with peak preferred if the coat is to be worn with black tie. And it should ideally fall a couple inches below the wearer's knee.
Gray suede or yellow chamois gloves are the smartest choices to accompany a daytime Chesterfield in my opinion, as is a silk scarf. Choose black gloves for evening and a white scarf with white or black and white fringed ends will make a good partner at night so long as it is removed when the coat is checked. Oh, and a homburg hat. The time for Mr. Beaton's Coke in the photo has passed.