Image copyright Camilita Nuttall Image caption Camilita Nuttall will never forget her worst business lunch experience

Camilita Nuttall says it was the business lunch from hell.

It was the first time that she and a new contact had met in person.

Ms Nuttall, a UK motivational speaker, says the man gave no explanation for turning up half an hour late at a London restaurant, and then proceeded to talk purely about himself.

To add insult to injury, she says he then told her that she wasn't qualified to run her own business.

And all this while he ordered the most expensive main course, and told Ms Nuttall that she'd have to foot the entire bill.

"It was the worst," says Ms Nuttall, 42.

Perilous menu

First things first, a business lunch isn't going out for a bite to eat with your mates from the office - that's socialising with colleagues.

It is instead a business meeting, usually in a restaurant, and typically with someone from another organisation, or at least someone who doesn't work in your team.

And the conversation will include business matters - be it talk about a sale, agreement or understanding that benefits both parties.

Image copyright Getty Images Image caption Lots of things can go wrong during a business lunch

You might think that going for a business lunch is a simple thing, but it is in fact beset with a whole menu of potential perils and pratfalls.

From the choice of venue, to what food you pick, whether you order alcohol, and how you share the bill, any number of things can go wrong.

Talking politics and religion is almost always a complete no-no, but what if an innocent chat about current affairs quickly turns to President Trump, Brexit or Scottish independence?

We asked some etiquette experts and business coaches to guide us through the minefield.

'Avoid messy food'

The first issue for someone organising a business lunch is the choice of restaurant.

"You need to find somewhere with a careful balance of ambience," says Jenny Flintoft, a leadership consultant based in the north of England.

Image copyright Boltenkoff Image caption It is perhaps best not to order food that is messy or difficult to eat

"I tend to favour a restaurant that is buzzy enough that conversations can be had without being overheard in a deathly quiet restaurant, but not one that has lots of background music, as the voice raising makes having a meaningful conversation very difficult."

Ms Flintoft also notes the importance of choosing the right dishes.

"I personally steer clear of corn on the cob, as it can easily get stuck in teeth," she says. "[I would also avoid] spaghetti or foods with sloppy sauces, or anything that requires a lot of effort to eat, such as shellfish.

"During a business luncheon I want to concentrate on my fellow diner, not battling with the meal."

To drink or not?

You also need to bear in mind the ethical or religious food rules that the other person may follow.

For example, ordering the foie gras followed by the veal might not be a great idea, and booking a restaurant that specialises in suckling pig could cause offence.

Image copyright Getty Images Image caption Picking a restaurant that specialises in pork or ham may not be a good idea

When you have reserved a table in a hopefully appropriate restaurant, one of the biggest questions that lunchtime is - to drink, or not to drink?

British etiquette expert Jo Bryant says that alcohol is best avoided because the social atmosphere of a restaurant "can easily let us forget that the lunch is for business purposes".

She continues: "Add in a glass or two and you might be at risk of relaxing too much, and saying or agreeing to do something you might regret.

"It is important to stay sharp and maintain your professional gloss."

Image copyright Getty Images Image caption Hitting the booze may not be particularly wise

However, London-based business coach Phil Jones suggests a middle ground when it comes to the wine list. "Allow the other person to take the lead," he says. "Sometimes it is a loosening of the collar.

"It's a chance to get some deeper issues, to speak a bit freer."

'No sex or politics'

Even without alcohol, conversations over a business lunch can all too easily go awry.

Ms Flintoft says: "Some people launch very quickly into diatribes about a particular hot [political] potato, and there's a lot of those around at the moment, which makes me question their judgement.

"But there needs to be a good mix of genuine conversation versus pitching."

Image copyright Reuters Image caption It is usually best to avoid any political debate

Ms Nuttall says there should be a number of "no-fly" discussions. "There should be absolutely no talking about sex, politics, religion, bad talking other people or companies, or negatives about your own company or theirs."

Mr Jones says people should also guard against venting any personal problems they might be struggling with.

"One man's wife was having an affair, and I was the first person he'd confided in," he says.

"I was given the role of therapist by someone who was a complete stranger to me."

Who pays?

Wherever the lunch, and whatever the topic, William Hanson, a UK etiquette coach advises being mindful of the other person's time.

"The worst ones are where they drag on and your host thinks you don't have anywhere else to be," he says.

When it comes to picking up the tab at the end of the meal Mr Hanson has a simple rule.

"Whoever extended the invitation, and has made the reservation, pays," he says.

Image copyright Getty Images Image caption Should you always split the bill?

To avoid any awkwardness or uncertainty when the bill arrives, Mr Hanson suggests that the inviter goes one stage further, and gives his or her credit card details to the restaurant ahead of the meal.

"It takes away the nasty money dilemma at the end," he says.

Mr Hanson takes a more relaxed approach though if a lunch with a particular client or associate becomes a regular event. Under such circumstances he says that a "turn-taking arrangement can often be struck".

Ms Nuttall adds that she often thinks that if one of the parties has travelled a long distance, they should be treated to lunch. But normally she suggests that the bill should generally be split equally.

Follow Business Brain series editor Will Smale on Twitter @WillSmale1