Two hands cupped together catching water, droplets streaming from the fingertips into a blue rippling body of water, with a pink wristwatch visible on the arm.

Brabners advises on sale of GMS Services to Complii

The sale marks the beginning of a new chapter for the specialist water and mechanical services business.

Our corporate team has advised Carl Ollerton and Gemma Ollerton on the sale of family-run GMS Services to Complii, marking the beginning of a new chapter for the specialist water and mechanical services business.

Established in 1997 by Howard Parry, GMS Services specialises in water hygiene, water treatment, Legionella compliance and mechanical services. Headquartered in Wigan with an additional operational hub in the Midlands, the business operates nationwide with a team of approximately 50 people.

A new chapter for GMS Services

After taking over the business from her father, Gemma Ollerton and her husband Carl Ollerton continued to build on its foundations, developing GMS Services into a respected national service provider while retaining the family values and personal approach at the heart of the business.

Having received numerous approaches from prospective purchasers over the years, it wasn’t until Complii approached Carl and Gemma in late winter 2025 that an opportunity emerged that felt like the right fit.

For them, the decision was about more than the commercial aspects of the transaction. They wanted to find a buyer that shared their values, recognised what had been built and could offer a positive future for both the business and its employees.

The shared vision, complementary objectives and mutual commitment to delivering high-quality services gave them the confidence to explore the opportunity with Complii further.

Supporting future growth

The acquisition provides GMS Services with additional infrastructure, specialist expertise and wider organisational support as it enters its next stage of growth.

As part of Complii, GMS Services will have access to central support across health and safety, human resources, recruitment, financial management, commercial operations and sales. This will allow Carl and Gemma to focus more of their time on the business’ core operations, customer relationships and future growth opportunities.

The acquisition also creates opportunities for the wider GMS Services team, with the backing of a larger organisation supporting investment in its people, the development of new capabilities and career progression as the business continues to grow.

“As this was our first business sale, we were stepping into the unknown and naturally had some apprehension about what to expect. Despite the due diligence process being intense and at times stressful, Mairead, Danielle and the wider team provided us with constant reassurance, guidance and calm support throughout the entire sale.”
Carl Ollerton, Technical Director, GMS Services

Advising on the transaction

As first-time sellers, Carl and Gemma instructed us to provide legal advice throughout the transaction, with Mairead Platt, Nikki Whittle and Danielle Phillips leading the team.

“It was a pleasure to work with Carl and Gemma on the sale GMS Services to Complii. Having built a successful business, it was important that they felt comfortable not only with the terms of the transaction, but with what the deal meant for the business going forward. We were delighted to support them throughout the process and help to deliver an outcome that provides a strong platform for the next chapter of GMS Services.”
Mairead Platt, Legal Director in our corporate team

Talk to us

As one of the UK’s most active legal teams for merger and acquisition activity, our award-winning corporate lawyers provide pragmatic and proactive support throughout complex business transactions. We take the time to understand each client’s business, key stakeholders and deal priorities before tailoring our approach around what matters most to them.

Discuss your plans by calling 0333 004 4488, emailing hello@brabners.com or completing our contact form.