At the start of this year, among the snowy Swiss slopes of the Davos business get-together, Rhian-Mari Thomas was ready to make an elevator pitch to the UK’s future chancellor, Rachel Reeves.

The chief executive of the Green Finance Institute (GFI) – a government-backed body that helps create and promote pro-environment financial products in the UK – had grown increasingly concerned about Labour’s £28bn green investment pledge.

The party should not have even considered using that much taxpayer cash, Thomas argued. Instead, it should engage with private investors who were already keen to pour money into big green projects. “I was very frustrated,” Thomas recalls, “and I said as much.”

Her pitch to Reeves was that the GFI should help steer Labour’s vision for a national wealth fund, ensuring it came at a lower cost to the public purse.

She told the then shadow chancellor that Labour needed the finance industry “in the room, to actually identify what exactly the obstacles are and where government money can be most impactful”.

Not long after, the £28bn pledge had been cut in half and soon Thomas was chairing Labour’s national wealth fund taskforce, convening heavy hitters such as former Bank of England governor Mark Carney, alongside the chief executives of Aviva, NatWest and Thomas’s former employer, Barclays. It led to the creation of the £7.3bn fund, launched just days after Keir Starmer’s landslide election victory in July.

It was a professional coup, and a vindication of Thomas’s decision in 2018 to leave banking for a role more aligned with her green roots.

Raised in Cardiff in the 1970s, Thomas was heavily influenced by her parents’ efforts to minimise their carbon footprint. The family stopped eating red meat in response to cattle farming practices across the Amazon, and her father – an economist and university lecturer at Cardiff business school – shunned the family car in favour of the local bus. “A lot of people in our neighbourhood thought he’d lost his driving licence,” Thomas says.

In her early teens, Thomas set up paper recycling at her high school on Barry Island and led a campaign to reduce the use of harmful chlorofluorocarbons found in the hairsprays that held up the gravity-defying hairstyles of the 1980s.

She left home to study physics at the University of Bath, followed by a PhD at Trinity College Dublin. But by the time she was looking for her next challenge, Barclays’s investment bank had come knocking.

“All this was new to me,” Thomas says. “I didn’t know the difference between an investment bank and a post office.” But Barclays Capital – then led by Bob Diamond, later to become the bank’s chief executive – was on the hunt for recruits with master’s and doctorate degrees, and offered a whopping one-off payment of £4,000 to students who performed well on its psychometric tests. “This was like riches beyond Croesus at the time,” she says.

She was soon navigating leveraged finance and private equity deals. After the credit crunch, she shifted into retail and corporate banking, and later became chief commercial officer at the bank’s credit card division, Barclaycard.

But by 2016, Thomas had hit a wall. She had watched as dozens of countries signed the Paris agreement the previous year in an effort to limit global heating. She wanted to do more. “I was just thinking, ‘is this really the best use of my energies, and the expertise and everything I’ve learned to do so far?’”

Thomas realised that sustainability debates were too divorced from business concepts – and that the City would change only if there were a credible financial incentive. “For something to take off within a profit-led organisation, it needs to be generating profit,” Thomas says. “And for something to be sustainable, it also needs to be commercial.”

In 2017, she launched a green banking council through Barclays that was credited with creating the first green mortgage product, offering customers discounts on more environmentally credible properties. Over time, she acquired a formal role as Barclays’s first head of green banking. “It really wasn’t a question any more. This was obviously what I was going to have to do with the rest of my career,” she says.

So when the UK government and the City of London Corporation launched the GFI in 2018, Thomas knew her next move.

Under her leadership, the institute has advocated new finance products such as local climate bonds and green rental agreements, and established an environment-friendly mortgage training programme. The GFI has also pushed for government guarantees to back developers’ investments in carbon capture technology, and the creation of special loans which investors start repaying only when green infrastructure – such as electric vehicle charge points – comes into use.

If we want firms to stop ­making money from polluting industries, they need credible alternatives, Thomas argues.

“People who work in the City are not stupid people. And if they can see an opportunity to make profitable, risk-adjusted returns for their organisations … they will do those trades all day.

So you’ve got to ask yourself, why is that not happening? And it’s a very lazy narrative to say it’s not happening because these people are evil.”

But Thomas is “not an apologist for the banks”.

“If I felt that going around criticising the banks was the most impactful way of achieving that, I would do that,” she says.

“Obviously, I wish they would move faster. But I equally understand how their business models work. And that’s what makes the GFI powerful, as a genuine partner to the finance industry, bridging those conversations with government. Because we need to help with the heavy lifting of removing some of those obstacles.”

CV

Age 51

Family Lives with long-term partner.

Education BSc in physics, University of Bath; PhD in physics, Trinity College Dublin.

Pay Undisclosed.

Last holiday A week in Provence with family and friends.

Best advice she’s been given “‘Dyfal donc a dyr y garreg’ – a poetic Welsh proverb that translates in English as ‘persistent tapping will break the stone’. A reminder that perseverance is key to achieving results.”

Biggest career mistake “Failing to take advantage of international opportunities during my career.”

Phrase she overuses “Amazing!”

How she relaxes Cooking, running, books and music.