Men wear fewer suits today, as we all know. But they retain the need for a jacket, if only to appear smart or professional.

Two of my friends, a doctor and a teacher, are particular examples. Their jobs do not require them to wear a suit, yet a jacket is very useful to have on the back of the chair (or, better, on a hanger on the door), to be put on for a meeting or consultation.

They do not know what this jacket should be. The materials are unfamiliar and the possible retail locations unknown. Men in their position often end up wearing either a suit jacket (shudder) or a tweed jacket (perhaps not smart enough).

Here is my advice.

The classic solution would be a navy blazer. Without gold buttons (dark blue or dark brown instead) and made out of a soft, pliable cloth like cashmere, lambswool or angora, or in a supple weave like hopsack.

Suit jackets are made from wool that has been treated (worsted) to make it smooth and sharp. It is too smooth and sharp to go with the cotton of your khakis, jeans or moleskin trousers.

Navy is the smartest colour, but it is too formal for some people’s needs. It is also less versatile, not quite making the transition from office to pub. For these men, the colours they should look for are light grey and brown. In the same soft cloths, perhaps with a herringbone pattern or Donegal tweed (the spotty one) to give some surface interest.

So where do you get one? If you can afford it, go to a tailor. After all, as you are only getting a jacket, the price will be about a third less than a suit. At Graham Browne you’d be talking around £600.

If you can’t afford a tailor, Ralph Lauren is the default choice. I have a beautiful, pale-grey camelhair model from there that has only got better with age. Then try Brooks Brothers, Brioni or Kiton. Trunk Clothiers stocks the best range of casual jackets from brands like Piombo, Aspesi and Caruso. And designers like Gucci and YSl do good unlined versions. Among the best of British are Paul Smith and Dunhill.

Go to a tailor if you can though. Take a look through Harrisons’ Moonbeam bunch and have something made with patch pockets, a half lining and variegated horn buttons.

Combination at top courtesy of Brunello Cucinelli