Origins of WSP Williams Sale Partnership was established in 1969 in England by Chris Cole, Geoffrey Williams, John Sale, and Geoffrey Middleton. In 1976, it was a founding member of the Building Services Research and Information Association (
BSRIA). It was first listed on the
London Stock Exchange in 1987. In August 2011, Genivar Inc. and Montreal-based architectural firm
ARCOP announced an alliance.
Takeover On 7 June 2012, Genivar made a
friendly takeover cash offer of
£278 million (
C$442 million) for WSP Group plc, headquartered in
London. The offer was backed by WSP's
board of directors as well as investors holding 37% of the company's shares, and the takeover was completed on 1 August 2012. This merger created a professional-services firm with approximately 15,000 employees, working in over 300 offices worldwide. The company reorganised its corporate structure on 1 January 2014, to create a parent company named WSP Global Inc. and adopted the common brand of WSP.
Subsequent acquisitions In October 2014, WSP completed the purchase of New York-headquartered professional services firm
Parsons Brinckerhoff from
Balfour Beatty for US$1.24 billion. The company has a network of approximately 170 offices and nearly 13,500 employees on five continents and became a wholly owned independent subsidiary. Together, WSP | Parsons Brinckerhoff is one of the largest professional services firms in the world with approximately 32,000 employees in 500 offices serving 39 countries. In early 2015, WSP announced plans to expand to 45,000 employees by 2020. In October 2016, WSP purchased Mouchel Consulting from the
Kier Group for approximately £75 million. In January 2017, WSP | Parsons Brinckerhoff announced that it would assume the name "WSP", effective from May 2017. In August 2017, WSP made a takeover bid for
Opus International Consultants. In July 2018, WSP announced its intention to buy Berger Group Holdings Inc., parent of the group of companies operating under the name of
Louis Berger Group, a Morristown, N.J.-based international professional-services firm, for $400 million. In February 2020, WSP acquired US-based environmental consulting firm LT Environmental (LTE). On December 3, 2020, WSP acquired Canadian-based geotechnical, earth-science, and environmental consulting firm
Golder for $1.14 billion. On June 1, 2022, WSP announced an agreement of sale with
Wood Group for the Environment & Infrastructure group (E&I) part of its business. The £1.6 bn acquisition was concluded in September 2022. In August 2022, WSP made an unsuccessful takeover offer to purchase
RPS Group for £591 million. In September 2022, RPS received a counter takeover offer from
Tetra Tech for £636 million with WSP opting not to increase its bid. RPS' shareholders voted to accept the Tetra Tech offer in November 2022. In September 2022 WSP also completed the acquisition of
Capita plc's property and infrastructure businesses GL Hearn and
Capita Property and Infrastructure for £60m . In December 2022, WSP announced plans to acquire a 700-person Swiss engineering firm, BG Consulting Engineers, based in
Lausanne with offices in France, Portugal and Italy. In August 2024, WSP announced plans to acquire 4,000-person US based consulting engineering firm, POWER Engineers, based in Hailey, Idaho with over 50 offices around the US and Canada for US$1.78 billion. In June 2025, WSP agreed terms to purchase British engineering consultancy
Ricardo. In December 2025, it was announced that WSP had signed an agreement to acquire TRC Companies, a US-based power and energy engineering and consulting firm, in an all-cash transaction valued at approximately $3.3 billion. The acquisition closed on February 24, 2026 and expanded WSP’s operations and workforce in the United States. ==Projects==