June 10, 2024

The 10 fastest-growing startup teams in the UK

For the second year running, climate techs dominate the list

2023 was a rough year in tech, and the UK was no exception.

Startups raised around half the figure of 2021’s record-breaking, $38.7bn year — pulling in $18.4bn.

While fundraising troubles have continued into 2024 (figures are currently on track to hit similar levels to last year) there are still several startups scaling at pace. 

Like 2023, climate tech dominates this year’s 10 fastest-growing startups, counting four companies among the ranks, following another record year on the fundraising roadshow for the sector. There’s also a fintech, biotech, edtech, foodtech, agritech and a GenAI startup on the list.  


Sifted used data from Dealroom to put together the fastest-growing UK startup teams by headcount over the last 12 months. To avoid results being skewed by early-stage businesses making lots of hires while growing quickly, companies must have raised at least $50m and have at least 25 employees to be considered.

1/ Weev

HQ city: Belfast, Northern Ireland

Founded: 2022

Headcount growth over the last 12 months: 167% to 48 employees

Weev operates an EV charging network across Northern Ireland. It raised a £50m round from Octopus Investments in May 2023 — the country’s largest ever VC round, according to Dealroom data. 

2/ Vertice

HQ city: London

Founded: 2021

Headcount growth over the last 12 months: 160% to 257 employees

London-based Vertice is a spend management platform that finance teams can use to gain visibility on their software and cloud spend. 

It’s raised $52.2m from investors including Bessemer Venture Partners and 83North — including a €23m Series B in January this year.


HQ city: London

Founded: 2017

Headcount growth over the last 12 months: 141% to 222 employees

Plant-based ‘meat’ maker THIS aims to have its first profitable quarter by the end of 2024, after appointing a new CEO and streamlining operations.

It’s the fourth largest brand in the UK’s plant-based category — and has picked up $53.9m in funding, from investors including Seedcamp, Backed VC and ITV. 

4/ Complement Therapeutics

HQ city: London

Founded: 2020

Headcount growth over the last 12 months: 100% to 28 employees

Complement Therapeutics is developing treatments for diseases in the area of ophthalmology. 

It’s raised $84.7m from investors, including a €72m Series A in April 2023.  

5/ GeoPura

HQ city: Newcastle

Founded: 2019

Headcount growth over the last 12 months: 95% to 82 employees

GeoPura uses renewable energy — like solar or wind — to create hydrogen-based zero-emission fuels, which it then converts to electricity.

It’s raised a total of $122m, most recently a £56m round in February this year, from investors including Barclays and UK Infrastructure Bank.

6/ Newcleo

HQ city: London

Founded: 2021

Headcount growth over the last 12 months: 91% to 434 employees

Newcleo is developing lead-cooled small modular reactors (SMRs) fuelled with radioactive waste — one of six types of “fourth-generation” reactors (also known as advanced reactors) which will begin to be rolled out in the 2030s.

It’s Europe’s only nuclear unicorn — valued between $1.3bn-$2bn, according to Dealroom estimates — and the best-funded nuclear startup in Europe by some margin. It’s raised a total of €487m in funding, including an €87m first close of a targetted €1bn round in May. 


7/ GrowUP Farms

HQ city: London

Founded: 2013

Headcount growth over the last 12 months: 88% to 79 employees

Vertical farming startup GrowUP has raised $134m since launching over a decade ago. Its most recent round came in February 2022, when it picked up £100m from Generate Capital. 

8/ Field

HQ city: London

Founded: 2020

Headcount growth over the last 12 months: 75% to 86 employees

The renewable energy infrastructure startup makes it onto Sifted’s fastest growing list for the second year running — after reaching number five in the 2023 edition.

Founded by now-collapsed energy supplier Bulb cofounder Amit Gudka, Field works with landowners and communities to build battery-based energy storage sites that supply the grid.

The LocalGlobe and Plural-backed startup raised £200m in July 2023 to expand its battery projects in the UK and to move into Europe. The round took Field’s total funding to £240m.

9/ Zen Educate

HQ city: London

Founded: 2017

Headcount growth over the last 12 months: 71% to 814 employees

Zen Educate is an online platform that connects supply teachers to jobs in schools. It’s raised $84.7m, including a $37m Series B in May this year. 

10/ Synthesia

HQ city: London

Founded: 2017

Headcount growth over the last 12 months: 71% to 361 employees

Generative AI unicorn Synthesia was one of the few European startups to hit the $1bn milestone in 2023, which came after it raised $90m in June that year. 

Synthesia uses GenAI to generate professional-looking AI videos from text and is one of the old guards of the GenAI space. The company has more than 50k customers, with nearly half of Fortune 500 companies using its tech to automatically generate videos with virtual avatars. The NHS, for example, has used it to make explanatory videos in different languages.  

Editor's note: This article has been updated from a previous version that included Field as the fastest-growing company. It has since been confirmed that Field's headcount in May 2023 was 49 and has increased to 86 in the last 12 months at a growth rate of 75%.

Kai Nicol-Schwarz

Kai Nicol-Schwarz is a reporter at Sifted. He covers UK tech and healthtech, and can be found on X and LinkedIn