For most people, essay writing becomes a thing of the past as soon as they step out of university and prepare themselves for the world of work.

But for others, the dissertation is just the beginning. That is because it has become increasingly easy to make money out of the very thing students spend three or four years paying to do at university: coursework.

The essay writing industry – where a third party writes tailor-made pieces of work for paying students – is thriving. And as the briefest of online searches will show, there are now swathes of companies offering to help struggling undergraduates with their work in return for cash.

Ethically, there have long been doubts over the practice. But financially, there are fewer concerns than ever.

UKBestEssays.com, one of the biggest players in the essay-writing business, has grown 10pc year on year, it said, while the boss of one its rivals, Essay Writer, believes the industry is now worth around £100m.

Both companies have been in existence since 2003, and both have experienced a continued increase in demand.

Dr Thomas Lancaster, a lecturer at Coventry University, has been investigating the use of essay writing services for a decade, and coined the term “contract cheating” to describe the practice of paying for work online and submitting it as your own.

“It is a booming business,” he says. “There are so many sites available and the number is growing all the time. And it is not just online sites – there are all kinds of offline mechanisms as well, such as adverts around universities, in newsagents’ windows or on noticeboards.

“They must be advertising, getting work in, having enough writers, paying them and still making a profit – so there is a lot of money going around in this chain.”

In 2008, UKBestEssays.com comprised of  seven thousands people working from different parts of the globe. Now, they have an office in Arnold, Nottingham, and around 5000 full-time members of staff.

“We have 200 people in quality control who sit down and read essays all day,” says Daniel Dennehy, customer experience manager at All Answers. “These are all graduates and highly-qualified individuals who make sure the work we send out is exactly what it needs to be.”

The business model is simple. The established companies such as All Answers and Essay Writer both have a pool of writers who each have specialist areas. When a customer gets in touch, the essay is commissioned to the writer, who then takes a cut of the fee.

UKBestEssays.com – who last year had over 160,000 customers – charges £155 for an essay of  “undergraduate 2:1” standard, and £357 for an “undergraduate upper 1st” piece of work, while 42pc of their turnover goes to their researchers.

The average order for rival company Essay Writer is £350 but can rise as high as £10,000 or £15,000, according to general manager David Burton.

“It is an expensive service,” he says adding that the business will remain profitable “as long as there is demand”.

That demand has never been higher. But why?

A key factor is the rise in international students. According to the Higher Education Statistics Agency, there were 436,585 international students in the UK in 2014/15, up from 318,000 in 2004/5 and 164,000 in 94/95.

Between 60 and 70pc of all of Essay Writer’s customers are students who have come from abroad, Burton says.

“You get a lot of students coming over and I would say they are substandard compared to the local students,” he says. “Often they are coming to a university and have not got a clue about the style or how the lectures work, and they can’t follow it because English is their second language.

“When they go off to write their essays, they do not quite understand.”

Dennehy agrees, saying international students “are very highly academic but trying to portray something in a different language can at times be very difficult.”

He adds: “They might not understand what is being requested of them, so they come to us and get an expert to produce an example answer which is exactly how it should be, so they can read it, understand the theory and the models that are being used.”

Of course, these businesses have been accused of facilitating cheating, but both All Answers and Essay Writer stress that the essays they provide to customers are for guidance and should in no circumstances be passed off as the student’s own work.

However, as Burton says, “there are going to be students who do that and the industry can be tarnished because students do not use it responsibly”.

In its defence, he adds: “If you go to a hardware shop to buy a knife to cut steak with, the person who sells the knife responsibly to you does not know whether you are going to use to it to murder your husband.”

The second major reason behind these companies’ growth was the rise in tuition fees in 2012. Now they are paying more to go to university, students have more to lose.

Dennehy says: “One factor we are seeing is the high rise in tutor fees. Students want to have the best possible chance of graduating with a good degree.

“They don’t want to be debt-ridden and paying back their student loan for the next 25 years. They want to take full advantage of every opportunity out there.”

Lancaster, who has spent years trawling forums and essay-writing sites as part of his research, adds: “For the students it is about weighing up the risks – what happens if they fail?

“They may have to repeat a year and then they are looking again at a substantial amount of money. If they are an international student they may also be out of a visa, so they could have to leave the UK as well.

“The cost of failure is far higher than it has ever been so students are more willing to take the risk.”