24Haymarket
24Haymarket is a London-based private growth-equity and venture firm that backs early-stage UK companies with proven commercial traction across software, fintech, healthcare and climate tech, drawing on a network of more than 100 private investors. Its water bets back digital water: real-time water-quality monitoring and flood forecasting. As of 2026, 24Haymarket has backed 2 water companies.
Compiled by Antoine Walter, (don't) Waste Water, from official filings and direct intelligence in Leviathan.
The take
24Haymarket is not a water fund, and it would be the first to tell you so. The London firm is a generalist UK growth investor built around an unusual engine: the 24Haymarket Investor Network, more than 100 experienced private investors who put their own money in alongside the firm and take a board seat in what they back. Founded in 2012 by a crew out of private equity, including a former chairman of Candover, 24Haymarket backs UK companies that have shown early commercial traction across software, fintech, healthcare and climate tech.
24Haymarket's water exposure is small and pointed, and it tells you how this firm thinks about the sector. Its two water bets are both digital water plays, not pipes or treatment plants: WATR builds solar-powered buoys and probes that stream real-time water-quality data from rivers and reservoirs, and Previsico forecasts surface-water floods up to 48 hours ahead. The thread is water as a data-and-risk problem, the kind of software-shaped opportunity a generalist tech investor can actually underwrite.
24Haymarket has put real capital and a board seat behind both of its water companies rather than tucking them in as token green bets, and (don't) Waste Water rates its water commitment Committed. 24Haymarket is the kind of investor I watch to see whether mainstream UK tech money starts treating water as a fundable software category rather than a worthy footnote, and on this small sample it is putting cheques where the thesis is.
Water Commitment Score
Compiled from official filings, third-party records, and direct intelligence from investors and founders, in Leviathan · recomputed monthly · as of Jun 2026.
How they invest
Portfolio · 2 water companies
Invests alongside
Highlighted = profiled on (don't) Waste Water.
Frequently asked
- What does 24Haymarket invest in?
- 24Haymarket invests in early-stage, high-growth UK companies that have shown initial commercial traction, across enterprise software, fintech, healthcare, cybersecurity and climate tech. In water, 24Haymarket backs digital-water companies: real-time water-quality monitoring and flood forecasting, rather than physical treatment or infrastructure.
- Who runs 24Haymarket?
- 24Haymarket is led by co-founder and CEO Paul Tselentis, formerly of The Carlyle Group, CCMP Capital and Lehman Brothers. He works alongside co-founders including Marek Gumienny, a former chairman of Candover, plus an investment team that draws on the firm's network of more than 100 private investors.
- What is the 24Haymarket Investor Network?
- The 24Haymarket Investor Network is a group of more than 100 experienced private investors who commit their own capital alongside the firm and often take board seats in portfolio companies. This network model, rather than a conventional blind-pool fund, is what distinguishes 24Haymarket and gives founders hands-on operator support.
- How many water companies has 24Haymarket backed?
- 24Haymarket has backed 2 water companies, according to (don't) Waste Water's tracking: WATR, a real-time water-quality monitoring platform, and Previsico, a surface-water flood-forecasting service. (don't) Waste Water rates 24Haymarket's water commitment Committed.
- Where is 24Haymarket based?
- 24Haymarket is based in London, on Haymarket itself, with a regional office in Edinburgh, Scotland. Founded in 2012, 24Haymarket invests across the United Kingdom and has deployed capital into more than 50 UK companies through its investor-network model.