The deal is expected to complete in early 2021 and includes all the 1,200 employees, contracts and 13 offices in the UK, Singapore, Vietnam, the Philippines, Hong Kong and mainland China

The business will be rebranded Binnies and will increase the overall RSK headcount from 4,300 to 5,500 employees worldwide.

Binnies will add £160m to RSK’s annual turnover, which has increased significantly in recent years from £147m in 2018 to £287m in 2020.

It will expand the number of countries in which RSK is present from 27 to 31 and significantly add to RSK’s existing Asian footprint.

Strengthening its presence in the water sector is a key strategic aim for RSK.

The group also acquired the UK-based Water Research Centre (WRc) and its 350 employees last August and acquired Ireland-based water engineer Nicholas O’Dwyer and its 200 employees last March.

RSK chief executive officer and founder Alan Ryder said: “This acquisition marks the most significant growth in our 31-year history, positions RSK as a market leader in the water sector and provides a springboard for RSK into the East Asian markets.

“The addition of Binnies to the group will greatly enhance RSK’s ability to address climate change, green growth and water and sanitation services at a global level through applied engineering excellence.

“Binnies brings incredibly valuable specialist expertise in all areas of the water utility sector; flood and coastal defence planning and design; specialist environmental services; digital and data services; construction management and commissioning; and operations, thereby bringing a true end-to-end client service offering.”

Managing Director of Binnies in Europe Scott Aitken said: “I am delighted with the acquisition by RSK of what will become the new Binnies business, an RSK-owned company, and how, with the combination of technical excellence, leading digital technology capability and end-to-end service offering, we will be at the forefront of assisting our clients solve these complex challenges efficiently and effectively.”

RSK’s 2025 growth and diversification ambition is to become the largest privately-owned environmental and engineering business in Europe, employing 10,000 people and to turning over £1bn annually.