Style or fashion rules are everywhere. Weekly we read what we can and can't wear and, while much of it is sensible, some is just repeated received wisdom with very little basis in either sense or aesthetics. Examples are 'No brown in town', 'blue and green should never be seen', 'older men shouldn't wear jeans/t-shirts' etc etc.
I try to avoid telling people what not to wear, but I have been guilty of passing on nuggets of wisdom. One example was the 'rule' that trousers worn with formal wear; morning suits or evening wear, should not have turn-ups (cuffs) as they are found only on less formal wear. With this in mind, I was interested to find this image of Cecil Beaton wearing morning dress with beautifully cut trousers with turn-ups.
They work; giving, in my view, balance to the whole look. It's noteworthy also how the cropped double-breasted waistcoat elegantly lengthens his legs, adding to the success of the turn-ups, which can make legs look shorter. The lesson is to trust your own judgement in these matters, or discuss your thoughts with a tailor, stylist, blogger or friend whose taste you respect.
Having said that there are some rules I would never break myself. Wearing a tie with the shirt's top button undone is one. Do you have any examples of non-rules or rules which really can never be broken?