The Berkshire factory was first opened by Forrest Mars in 1932 and produces some of the most recognisable brands in Mars’ portfolio, including its eponymous Mars bars (which were conceived at the site), Galaxy chocolate, Snickers bars and Maltesers products.
The first phase of the £190 million investment was kicked off in 2023 and will continue through to 2028, expanding advanced manufacturing, digital capabilities, sustainability initiatives and workforce upskilling at the Slough site.
Mars says that £32 million of the total £190 million investment is still planned for 2027 to 2028, building on more than £118 million in UK capital investment across its Snacking, Food and Petcare businesses in 2024 to 2025 alone.
Through this investment, the firm will be introducing what it is calling “state‑of‑the‑art” manufacturing capabilities at the site, which combine robotics and artificial intelligence (AI) with upgraded machinery.
Advanced cooling systems and energy‑efficient utilities will also be installed to improve performance and sustainability across the facility.
The US-based multinational adds that these investments reinforce the UK’s strategic importance to the company, and showcase its nine‑decade contribution to the UK economy and its continued commitment to investing in local industries, skills and communities.
Notably, Mars has said that it will be deploying “digital twin technology” at the factory, which will use AI‑driven data to optimise production and enable precise process control, consistency and uniformity across product lines.
The planned upgrades will also allow for “real‑time” decision‑making on the factory floor and will reduce waste.
“This investment reflects our confidence in the UK as a hub to manufacture and innovate,” said Adam Grant, general manager, Mars Snacking UK & Ireland.
“In taking a long‑term view, we are ensuring our operations remain world‑class, competitive and fit for the future. Our Slough factory is deeply rooted in our heritage, and as a proud family‑owned business, we are committed to investing in a future that creates lasting, positive impact for the communities in which we operate.”
Alongside meeting UK demand, the Slough site also produces chocolates for distribution in the Irish and Dutch markets.
The site remains a significant local employer, with 1,850 people currently working at the site – many across multiple generations of their family.
Business and trade secretary Peter Kyle added: “This £190 million investment by Mars is a strong vote of confidence in the UK as a place to manufacture and innovate.
“For nearly a century, the Slough factory has produced some of the world’s best‑loved brands, and this investment shows global businesses continuing to back British skills, workers and industry.”
