Entrepreneur who built £5m brand before 23 reveals how his business became 'more than a side hustle'

Patrick O'Donnell
Sat, 04 Apr 2026 23:01:01 +0000

A teenage business idea rarely turns into a multi-million-pound premium men's jewellery enterprise, but James Demetriades is an exception to this rule.

The founder of Undeniable London launched the brand with his brother in 2019 and scaled it to more than £5million in revenue before the age of 23 without a penny of outside investment.

Mr Demetriades: "I realised Undeniable London could be more than a side hustle from the day I started, and that's the reason it became a success.

"When I do something, I do it properly, with research, preparation, planning, and most importantly, obsessive execution. There was never a single lightbulb moment because I never treated it as a side hustle in the first place."

"My brother and I launched the brand in 2019, and from day one, we were reinvesting every penny back into the business. We studied the market, understood our customer, and built something we genuinely believed in.”

"That level of conviction is what separates the people who scale from the people who dabble."

Mr Demetriades said his mindset was shaped by his upbringing, becoming financially independent at a young age: "I grew up financially self-reliant from 12 years old.”

"Having zero safety net was the only fuel I needed to succeed in business. When there are no other options available to you, you go all in. Most people live their whole life scared about what happens if they fail, but failure to me is not trying and not taking the risk to go and achieve my purpose.”

"I learned very early that nobody was coming to save me, and that clarity is actually a gift. It strips away hesitation. Every decision I made in the early days of Undeniable London carried real weight because there was nothing to fall back on, and that forced me to be sharp, disciplined and decisive."

According to Mr Demetriades, performance marketing was key to the company’s early growth, with emphasis being put on understanding how to turn a profit on TikTok, Instagram, and Google.

This was "single-handedly the lever" that allowed Undeniable London to grow from a £3,000 a month business to earning £85,000 despite still being in its infancy.

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He added: "Mastering performance marketing changed everything for us. We spent hours studying ad creatives, testing audiences, analysing return on ad spend and refining our approach week after week.

"A lot of people get drawn into tactics that look impressive on the surface, things like influencer gifting or viral content strategies, but if your paid acquisition engine isn't dialled in, none of that matters.

"Paid advertising gave us predictable, scalable revenue, and that predictability is what allowed us to reinvest with confidence."

Mr Demetriades noted that running a direct-to-consumer brand requires strong financial discipline behind the scenes.

"The hardest part of running a direct-to-consumer brand is staying extremely financially organised and understanding where you are allocating your capital at all times.”

"You have to stay focused on the big picture plan rather than getting pulled into the short-term minor operations that can consume your day if you let them.”

"One wrong stock order or a poorly timed ad spend increase can set you back months. The founders who survive in this space are the ones who treat it as a serious financial operation, not just a creative project."

Mr Demetriades cited that scaling the business required him to step back from day-to-day tasks, transitioning from "operator to leader" when the time came.

"I realised it's impossible to succeed in e-commerce on your own. You need a team, you need a vision, and great people to build this empire alongside.

"The biggest thing I had to unlearn was trying to do everything myself. In the early days I was packing orders, running ads, handling customer service and managing suppliers all at once.

"That gets you off the ground, but it doesn't scale. Learning to trust other people with parts of the business I had built from scratch was uncomfortable, but it was the single most important shift I made.”

Looking ahead, Mr Demetriades believes the UK offers "unfathomable amounts of opportunity" for entrepreneurs, particularly for those who operate online..

"When you learn how to create valuable products and then learn how to market and sell them through various marketing strategies, you put yourself in a position where you exchange no time for money.”

"It can be run anywhere in the world and is heavily automated with the use of AI and digital software. The UK has an incredible pool of young talent, and I think we are going to see a wave of founders in the next few years who build global brands without ever setting foot in a traditional office."