As I type this piece, I am of course wearing three-inch heels. How could I possibly produce high-quality work otherwise? I've tried working in flats, but the words just all came out wrong.

If it sounds ridiculous to suggest that a woman's workplace performance should be connected to her footwear then perhaps you haven't yet heard the story of Nicola Thorp, a temporary worker who was reportedly sent home without pay from finance company PwC after she refused to conform to a rule saying she had to wear 2-4 inch heels. Following a media outcry, outsourcing firm Portico, which set the "appearance guidelines", has changed its policy with immediate effect.

Thorp's story has surprised many, but it is just the tip of the iceberg. Women's dress and appearance, including make-up, hairstyles and accessories, are regularly policed across a wide variety of different workplaces.

Cabin crew are famously held to exacting dress and appearance codes, with women around the world reporting restrictive and painful requirements to wear not only high heels, but also a wide variety of other tight, uncomfortable and impractical clothes.

Female cabin crew at Japanese airline Skymark complained in 2014 when the airline introduced a new miniskirt uniform, which women said exposed them to sexual harassment from clients. Just last year, cabin attendants at El Al Israel airline protested a company policy that saw them forced to wear high heels at least until all passengers were on board and seated, a common requirement within the industry.

And it was only recently that the Cannes Film Festival faced a backlash after mandating that women would only be admitted to a gala screening if they were wearing high heels, resulting in a group of women in their fifties being turned away.

But sexist dress codes don't have to be an official part of an organisation's code of conduct to cause headaches. Numerous women working in industries such as hospitality and events promotion have written to the Everyday Sexism Project describing enormous 'unofficial' pressure to wear uncomfortable, tight or revealing outfits as 'part of the job'. Often in these circumstances women do not have an HR department to rely on or a long-term contract to protect them, so they are very vulnerable to losing their jobs if they dare to protest.

One woman worked at a pub where she was required to wear a kilt and knee-high socks. She received regular verbal harassment from customers asking about what she was wearing underneath, was called a "slut" and had one male customer lift up her kilt while she was working.

Numerous women working in industries such as hospitality and events promotion have described enormous 'unofficial' pressure to wear uncomfortable, tight or revealing outfits as 'part of the job'

Another woman, who did promotional work at an event, said she was provided with a very "skimpy costume" and had male attendees asking to pose with her for photographs, but first requiring her to turn around so their photograph would be taken with her bottom in the picture.

What is particularly frustrating is that women are often attacked from all sides at once. We regularly hear from women who have been told they should wear higher heels, or lower cut tops, to 'keep clients happy'. One woman, for example, was told: "Barmaids should look good for the customers."

On the other hand, we also receive large numbers of testimonies from women who are lambasted for looking 'unprofessional' if their skirts are deemed too short or their heels too high.

One woman, who worked in a university library where there was no official dress code, was taken aside by her male boss to tell her that her clothes were "distracting" and "showed too much skin". It was the middle of summer and she was wearing an ankle-length sun dress.

Another, who worked in a bar where the dress code for women was a short miniskirt, was disciplined by her manager because she bent her knees when bending down to pick up glasses from under the bar. Her manager told her she had to "keep her legs straight so the men got a thrill as part of their drinking experience".

Such is our universal hypocrisy and hyper-sexualisation of appearance and attire that women are often trapped in a lose-lose situation. While Portico demanded high heels, similar recent stories have seen female lawyers being warned against wearing "trashy heels" that "send the wrong impression", while others have been told not to wear black, or to sport clanky jewellery, or to reveal any cleavage.

In one recent survey, two thirds of British bosses admitted they would discriminate against a woman who came to an interview not wearing make-up. Yet just two years earlier another study was published, claiming "one in three bosses now think women wear too much make-up to work".

The only way to move forward is to move away from the idea that a woman's looks, body or dress define who she is as a person or a professional, or how highly she is valued.

The only way to move forward is to turn away from the idea that a woman's looks, body or dress define who she is as a person or a professional. This does not mean no workplace should ever have a dress code, but it shouldn't be gendered in a way that polices women's dress and bodies more than that of their male colleagues. While it is easy to say that employers have the right to demand their workers look smart, we also need to confront the fact that there is deeply ingrained prejudice inherent in our societal idea of what constitutes 'smart' in the first place.

This prejudice is not restricted to sexism – in a famous recent example the US army updated its grooming standards to exclude a number of hairstyles popular with black women with natural hair, suggesting that there was something less smart or acceptable about those styles.

There is also often an inherently sexist assumption about intent in the implementation of dress codes. To demand or ban high heels, cleavage or tight clothing is to suggest that a woman wears such things in a deliberate attempt to seduce or distract her clients or colleagues. In reality, she is probably dressing for herself alone. Why should she be responsible for anybody else's reaction? She deserves to be treated with dignity and respect, regardless of what she is wearing.

One young woman who wrote to Everyday Sexism described a training session for a job at a museum, in which men were told about specific items of clothing they were expected to wear or not to wear, while women were simply told: "Ladies, make sure you dress appropriately; don't dress to start something". Bewildered, she asked: "What am I going to be starting in a museum?" Another woman wrote about being disciplined for wearing a short dress to work, because her manager said the men were staring at her, "being distracted, so work is disrupted". She added: "Not a single guy in the room was reprimanded or even talked to about the 'disruption'."

In 2016, requiring women to wear often impractical and painful high heels in the workplace is ridiculous. But so is demanding they wear a certain amount of make-up, reveal/hide their cleavage or measure their skirt to within a centimetre. Bosses should stop putting so much emphasis on their female employees' appearance and concentrate on their performance instead.

Laura Bates is the founder of the Everyday Sexism Project