Never start a business with friends or family. Never mix business with pleasure.

They were at the heart of traditional advice from consultants to start-ups.

But one Newport-based firm says any blinkered adoption of historic business rules could be an expensive mistake for modern entrepreneurs.

A father, his son, and two close friends started United Commercial Finance in 2017.

Sixteen months on, the invoice finance brokerage has negotiated £20m in client funding lines, opened two satellite offices in England, and is on course to smash its second-year projections.

The directors of UCF say that the existing friendship of its founders was key to their immediate success, and are now sharing five of the major benefits to others who want to set up a business and see profits from day one.

1. Natural pride in the success of your friends in and out of the workplace

"This is my number one benefit," said UCF director Chris Green.

"When you bring years of friendship into the office, each member of the team works naturally to help the others succeed. Each person wants the other to do really well. The office has becomes an extension of your friendship, not a threat to it.

"At UCF, we are all really supportive of the growth in our company, but it is not about the bottom line per sé. What we really thrive on is the positive effect doing well has on each other's families and lifestyles. Team success becomes addictive.

"And family is what we are all about. So when someone wants an extra few days here and there to spend time with their loved ones, the rest of us welcome it, never judge it."

2. It offers an invaluable support mechanism

"A new business venture can consume your life," said fellow director Joe Patrick. "It is very stressful, and those outside work can get very bored with your obsession very quickly.

"But with friends and family actively involved in the business, you are each other's support mechanism both in and out of work.

"In our office, for example, we regularly chat about life outside work. Equally, we can spend an evening out and chat really naturally about work. It is a really happy medium, and acts as a wonderful pressure valve.

"It's amazing how a frank discussion in a social setting can sort any potential problems and create good ideas within minutes.

"I know that if I had to spend my day focused on work, and then my evening focused on anything but work, my life would be intolerable.

3. Camaraderie and trustworthiness

Jos Patrick is Joe's son, and a fellow director of UCF. He says that a business run by family and long-term friends brings to the business a culture an instant feeling of total trust.

"In commission-based businesses, you could be forgiven for looking over your shoulder. You worry about others who want to benefit from your hard work.

"But when you work with people who you'd trust with your life, you don't ever worry about someone pinching your client. In fact, we spend more time actively helping each other to do well.

"In and out of work, we all support each other: that’s just what real friends and family do."

4. No learning curve when it comes to character

"Starting a new business is hard enough without worrying about the team gelling, whether they fit the culture you envisage, or want what you want for the business," said UCF director Andy Smith.

"But friends have already gone through a decades of the most personal, comprehensive two-way interview process possible.

"Before you even register the company, each of the team knows the others' strengths, weaknesses, character, work ethic, business expectations, what makes them tick, and everything else that makes a team work.

"So come your company's first day, you are all up, running and have the right team focusing on the business, rather than sifting through the piles of rose-tinted CVs created by consultants.

"Believe it or not, we've also had an ex-CV consultant offering us help to spot CVs written by other professional CV consultants.

"Maybe we are naive to think our business can be built on simple friendship, honesty and trust, without the need of a team of suits to make us fit in with their status quo.

"I guess we will see," said Andy.

5. A fun and caring family environment is attractive to both clients and potential employees

Andrew Major met the UCF team in a social setting and knew instantly where his future lay. Now a UCF financial consultant, he says that the close-knit relaxed culture is at the heart of the business's success.

"Any company can offer an excellent product or service, but build the team around decades of friendship and you have a fantastic working environment," said Andrew.

"Families and social lives are a big part of the work day, and such a relaxed atmosphere keeps any stress to a minimum.

"People buy people, so any business that combines a great service with a culture of real friendship, honesty, trust and fun, will be noticed by clients," he said.

"And when you treat clients as part of the team, they become an extension of that friendship, and even your best independent sales tool.

"At UCF, for example, around half of our business is built on referrals, so adding expertise and friendship can be a winning combination," said Andrew.

Cashflow specialists United Commercial Finance helps businesses get paid up to 95 per cent of their invoice amounts within 24 hours of sending them.