Our experts answer your most pressing style questions.

Rules, who needs ’em? Actually we all do, and menswear is full of them. But sometimes we don’t always realise the reasons behind them. Like, why do we leave the bottom button undone on a jacket? And can you wear black shoes with navy? Find out the answers below, alongside some advice on how to assemble a wardrobe of affordable essentials.

Send in your questions via our social channels or email dan.rookwood@mrporter.com and check back in next Friday for answers to three more.

Does the “leave the last button unbuttoned” rule go for overcoats as well as blazers and waistcoats?

Mr Luke Jacobs, via email

Good question. Before we answer it, a little revision of the button rule you mention. “Sometimes. Always. Never” is the easy top-to-bottom way to remember it for a three-buttoned tailored piece. The bottom button is never done up (unless you're wearing a one-button jacket, obvs). To do so is a schoolboy error, often literally.

Why? There are a couple of explanations. The most popular and plausible is that in the early 1900s, when the future King Edward VII was Prince of Wales, he became too fat to fasten the bottom button on his waistcoat and jacket, so his inner circle began to unfasten theirs so as not to offend – and it diffused from there. Another theory is a practical one: back when gentleman rode horses, it was more comfortable to have the bottom button undone when in the saddle.

Today, all suits are cut in such a way that it would look strange and feel uncomfortable to do up the bottom button. Leaving it unfastened allows for a freer range of movement, a longer stride, a hand in the trouser pocket. For waistcoats (or vests), if the bottom button is cutaway, it’s always left unbuttoned.

But what about overcoats? Generally speaking, I would still leave the bottom button undone. It looks less stiff. And if you are sitting down in your coat – for example when travelling on public transport – it will be more comfortable. However, in inclement weather, the practical outweighs the aesthetic. Given that the primary purpose of an overcoat is to keep you warm and dry, it is perfectly reasonable and acceptable to do up all the buttons to keep out the elements.

Is it acceptable to wear black shoes with navy trousers, specifically dark denim and chinos, or do the colours clash?

Mr Tyler Colville, via email

The darker the navy, the better they match. And then it’s less an issue of colours clashing and more about a possible jarring disconnect in formality. Of course, black shoes go very well with a navy suit. But with less formal trousers such as jeans and chinos? The hue of blue is crucial, as is the style of shoe. Personally I would be cautious of wearing a formal black leather Oxford shoe with most casual blue trousers. A more relaxed shoe style such as a black leather Derby or a brogue or Chelsea boot could work if the jeans or chinos in question are very dark navy, as you suggest. A rubber sole can also help to offset the formality of a shoe. But you’re on a surer footing if wearing something casual in black suede (a chukka or Chelsea boot, for example) or black leather or black canvas sneakers such as Common Projects Achilles or Vans Old Schools. Black shoes and lighter blue trousers present more of a colour clash and so such a combination is best avoided.

**I’m 21 years old and I’m looking to rebuild my wardrobe, but I have zero sense of direction or starting point. How should I go about this? **

Mr Jamal Abdur-Salam, via email

One could think of assembling a wardrobe the way a football (soccer) manager might pick his team: you need a strong spine of reliable stalwarts as your go-tos, plenty of versatility, and some creativity and flair up top.

Seeing as you’re 21, I’ll suggest some essentials that I think could work for your age, using brands that are appropriate and hopefully within reasonable budget. Most of these items should go together (they’re all pretty classic and the colour palette is safe). But for more inspiration click on each of these items and see how they have been styled on the site so you can get an idea of what else to wear with them, and so what other key items might be missing from your assortment.

**Trousers: **indigo jeans from Nudie, olive green chinos from Club Monaco, tan chinos from NN07.

Shirts: white cotton shirt, chambray button-down from J. Crew, white Club Monaco T-shirt and grey T-shirts from Velva Sheen, navy Lacoste polo shirt, Breton-striped T-shirt.

Shoes: white leather Converse, brown brogue Grenson boots, chocolate brown R.M. Williams Chelsea boots, polishable black lace-ups from Want Les Essentiels.

Tops: grey sweatshirt from Reigning Champ, navy V-neck John Smedley sweater, camel round-neck sweater from Theory.

Jackets: blue APC denim jacket, olive J. Crew bomber jacket.

Coat: grey Paul Smith overcoat, navy peacoat from Schott.

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