This is a classic summer semi-formal outfit which is appropriate for a professional setting most of the time.

The jacket is a silk / wool / linen blend. This gives it a combination of various properties that make it one of the best fabrics to use for casual or semi-formal summer jackets (usually not for trousers or suits though). The linen gives breathability and the wool gives it drape and crease resistance. The silk can add more of a sheen to the appearance but this one has a fairly matte texture.

The overall surface texture is important as it clearly separates it from the top half of a suit. This can also be achieved through the choice of colour, the construction and the styling. The flecks of white fabric among the brown give it texture and help it reflect light to give it more of a summer feel.

The example above is a classic Neapolitan construction with minimal shoulder padding, some chest drape and a “3 roll 2” button set up. There is no shoulder roping which differentiates it from the construction of a typical suit jacket. It is half-lined which helps keep it light and wear cooler.

The jacket is styled with 2 patch pockets at the waist which is more indicative of a sports jacket rather than a suit. The chest pocket is welted which is more traditional but it can also be patch if you want to make it more casual.

The trousers are made from fresco which is a high twist open weave wool fabric. These are the ideal semi-formal trouser fabric as they wear quite cool (due to the open weave) but also drape cleanly. This means that they won’t look unusual in an office setting as a fabric like linen can do. The colour chosen here is a mid grey. This is probably the most versatile colour for semi-formal trousers as it goes with a variety of shirts and jackets. It will go with white and light blue shirts (the majority of mens’ work shirts) as well as a range of jackets – the classic navy, browns and greens. It won’t go with grey jackets, however, but these are unlikely to be worn regularly anyway. Basically this type of trouser will be classic and subtly casual. It won’t stand out which means that you have a bit more leeway with other parts of the outfit. The trousers are designed with turn ups (a slightly more casual styling element) and side adjusters (which give a cleaner, more sartorial look). Slightly higher-than-usual waists are also a more sartorial option these days.

The rest of the outfit is made up of brown loafers and a classic white cotton shirt. These are very standard, ‘unshowy items’. The only thing that would be considered slightly unusual for an office is the choice of the jacket colour. Navy would be much more typical but it’s good to have something a bit more adventurous now and again. It could also easily be worn with a tie to bring it a notch up the formality scale. Something like a lightweight linen or knitted wool tie would harmonise with the rest of the outfit.