We all know the stereotype – the dreaded 'Karen' demanding to see the manager over a slightly cold plate of chips.

But a new study suggests that when it comes to complaining in restaurants, age and gender actually have little to do with it.

'Forget the stereotypes,' lead author Dr Adrian Martin, from Edge Hotel School at the University of Essex, said. 

'Restaurants need to be more aware of how to deal with the different types of customers which really exist to avoid issues escalating.

'Angry diners really do come in all shapes and sizes and our research found no evidence for the kind of stereotype promoted on social media.

'What we actually identified were three factors – including personality – that reliably predict whether a customer will speak up if there is a problem while they are having a meal out.'

Typically, the Karen stereotype refers to a highly opinionated character often associated with being female, middle class and middle–aged.

To test whether it holds true in real life, scientists tracked nearly 1,000 meals at 100 volunteer restaurants.

Analysis revealed people were more likely to complain when the meal was tied to a special occasion, such as a birthday, anniversary or celebration.

In those situations, diners generally had higher expectations, meaning service failures were less likely to be tolerated.

Customers were also more likely to complain when problems occurred before the visit, such as booking or reservation errors.

However, a friendly welcome appeared to be one of the best defences against a disgruntled diner – with customers less likely to complain when staff made them feel valued from the moment they arrived.

When it came to personality, the diners most likely to complain were people who felt a strong need to challenge unfairness, along with those who were more entitled and assertive.

Empathetic diners, meanwhile, were the least likely to raise a complaint.

Overall, the data on complaints showed no patterns across gender, age or income.

Men complained no more or less than women, older diners no more or less than younger ones, and higher earners no more or less than lower earners.

The study, published in the International Journal of Hospitality Management, also measured how restaurants handled mistakes once they happened. 

It found that 40 per cent of errors made by restaurants were never raised by customers, with diners choosing to stay silent.

A further 45 per cent of errors were mentioned by the customer and resolved well by front–line staff on the spot.

The remainder escalated, either to management or into formal complaints.

Dr Martin said: 'There are some real practical implications for restaurant owners from our findings.

'They show the importance of frontline staff as early customer interactions, such as greet–and–seat and being made to feel special on arrival can really help put people at ease.

'This significantly reduced both the odds of noticing a problem later and the odds of raising it.

'Creating connection and empathy with customers can make such a difference, while frontline staff having the confidence and knowledge to solve issues as they emerge can quickly reassure diners.'