After establishing the company in Oxford, United Kingdom, in 1994, David oversaw the growth of the business from a small UK operator into an environmental consultancies in the UK, with international operations across Africa, Australasia, Canada, Europe, and the US In 2000, the senior management team completed a management buyout and the company's name was changed to SLR Consulting Limited.

[12] SLR has made a number of acquisitions, beginning with the UK-based Waste Management Engineering Limited in 2005.

Then followed the UK-based landscape architect company Insite Environments;[13] the Canadian company SEACOR Environmental Inc.[14] the UK-based company FMH Consulting Engineers;[15] the Irish Dublin-based environmental consultancy CSA;[16] the specialist mineral planning, landscape and land management firm Bowman Planton;[17] the UK based Architecture and Planning Solutions[18] Alaska-based Hoefler Consulting Group;[19] Australia-based Heggies Pty Limited;[20] UK-based company Andrew McCarthy Associates;[21] South African based GreenEng[22] and Metago.

[25] In October 2013, Cooper Partnership - Chartered Landscape Architects was acquired in Bristol, UK; and in early 2014, the acquisition of HFP Acoustical was completed, adding offices in Calgary, Alberta and Houston, Texas.

In November 2014 SLR acquired the UK-based oil and gas solutions provider Challenge Energy,[26] and in February 2015 SLR acquired E.Vironment LLC, a Houston-based environmental management, health and safety, process safety, and transaction advisory firm.