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So much time is spent at the office with colleagues that blurred boundaries are almost to be expected.

But at what point does the line become so blurry that you risk looking foolish, upsetting team members - and even putting your career at risk?

According to 'Queen of Etiquette' Laura Windsor, there are clear-cut signs, including having a work wife or husband and using your phone during meetings (even if the conversation isn't directed at you).

Speaking to the Daily Mail, Laura said: 'Every workplace relationship should be based on mutual respect, professional boundaries and genuine goodwill.'

And committing any of the 11 acts below, according to the expert, violates unspoken office etiquette rules.

'Queen of Etiquette' Laura Windsor has revealed the mistakes no office worker should ever make (stock image)

Having a 'work husband' or 'work wife' is a no-go - especially if you're in a relationship...

A work wife or husband might be defined as a close, platonic friend providing emotional support in the workplace - but according to Laura, they can get sticky fast.

Laura said: 'There is nothing inherently wrong with enjoying a little light-hearted flirting.

'Most people like to feel appreciated at work; it can boost confidence, improve morale and even encourage better teamwork.

'However, these types of relationships need clear boundaries. What starts as fun can soon become emotionally draining, especially if you are unfulfilled in your personal life.

'If you find yourself thinking more about your work colleague than your partner on the journey home, or you are constantly comparing the two, or worse, dressing up 'just in case they do come in today', it may be the universe's way of telling you something is wrong.

'Sometimes the attraction has very little to do with the colleague, and more to do with your need for appreciation and attention that you are not getting elsewhere.

'And if your partner hears more about your work husband/wife than the words 'I love you', perhaps you need to re-think your priorities. Of course, things are much simpler if your work spouse bats for the other team.

'If you hear HR referring to your work husband or wife as an ongoing problem, it's time to back off and revisit those boundaries.'

Resist going on your phone during meetings...

It might be tempting to reply to a text - or even respond to a work email during a meeting, but according to Laura, it's not worth the risk.

She said: 'Checking your phone while someone is speaking sends a pretty clear message- and it isn't a flattering one.

'It suggests that whatever is on your screen is more important than the person speaking.

'It also shows you have to be constantly stimulated, you lack self-control and have a zero attention span.

'Good leaders give people their full attention, maintain eye contact, listen actively and offer thoughtful feedback.'

Don't eat at your desk (unless absolutely necessary)

Laura said: 'Sometimes there are deadlines you are left with little choice but to eat lunch at your desk.

'However, remember that your colleagues are trying to work, and eating like a caveman/woman may not be entertaining to most.

'Sit up straight, bring the food to your mouth rather than your mouth to the food, chew with your mouth closed and keep noises to a minimum.

'If you're unsure what you look like while eating, have a look in the mirror beforehand- you may be in for a shock.

And keep pungent dishes at home...

She continued: 'Not everyone appreciates the aroma of a fish drifting across an open-plan office.

'Our noses are sensitive appendages and even if you are enjoying your lunch, others may not. You want to be remembered for your professionalism, not your food choices.'

But never take others' food from the fridge

But where Laura strongly drew the line was picking at others' food in the communal fridge.

She said: 'Your stomach may be rumbling, but unless you haven't eaten for a week, resist the temptation to raid the office fridge.

'It suggests poor time management (you didn't have time to get yourself some food) and it's also stealing.

'It shows a lack of integrity because eventually you will be caught out and why damage your reputation over a sandwich?'

Avoid wearing open toe shoes... and don't even think about taking them off altogether

Laura said: 'Very few people arrive at work hoping to admire someone else's feet. Guys, it is unlikely that your hairy toes beneath the desk will enhance your professional image.

'Ladies, if you choose to wear open-toed shoes, ensure your feet are well groomed. Flip-flops and beach sandals, however, belong exactly where the name suggests - on the beach, not in a meeting room with clients.

'And whatever you do, resist the temptation to remove your shoes altogether. You may think your feet deserve to be aired, but your colleagues didn't sign up for this sort of experience.'

Don't change your shoes at your desk

Racing for the train in heels isn't ideal, but if opting for trainers and then swapping into your work shoes at your desk is a no-no, Laura said.

'Perfectly sensible but at your desk? If your workplace has a bathroom, use it - it's the right place for applying make-up, brushing your hair, adjusting your tie or admiring yourself in the mirror.

No one wants to hear your lengthy personal phone calls

Laura continued: 'Unless it is genuinely urgent, personal calls should be kept brief or saved for your breaks away from your colleagues - open-plan offices have excellent acoustics.

'Nobody wants to overhear an argument with your partner, a detailed account of last night's date or this evening's dinner plans.'

Skip going into the office when you're sick

You might feel pressure to go to work while sick, but according to Laura, it won't do you any good.

She said: 'While coming to work sick is admirable, no one is going to thank you for it if they are prone to getting sick easily. With air-conditioned open plan spaces, germs are easily spread.'

Discussing politics is a no-go

Laura said: 'Politics, religion and football all have one thing in common - they arouse passionate opinions, and workplaces are not the ideal setting for heated debates.

'People often judge others by their political views, and one bad remark can linger for years…and you will also probably regret it.'

And tread very carefully if getting drunk at the work pub

Laura's final word of advice was to avoid having one too many at the pub with colleagues.

She said: 'Alcohol lowers inhibitions, loosens tongues and occasionally encourages dancing that should never have happened.

'You'll probably become memorable - but for all the wrong reasons; and end up being the laughing-stock for years to come.'