In March last year, multi-disciplinary consultancy WSP announced plans to acquire Indigo Planning as part of a "drive to become the top planning consultancy in the UK".
In the wake of the merger, the two firms worked under the WSP | Indigo name, but from 4 May the combined planning consultancy team will trade under the WSP name.
The merger has seen 105 chartered town planners from both firms integrated into co-located offices in London, Manchester, Birmingham and Leeds.
A statement from the firm said that the integration has now been completed and "has seen the creation of a combined 'Planning Consultancy' team, where Indigo's industry-leading town planning team have combined with WSP's infrastructure planning specialists alongside the expert Environmental Asset Management (EAM) team".
Phil Villars, head of planning consultancy and EAM at WSP, said: "The creation of Planning Consultancy combines Indigo and WSP's expertise into one specialist offer for clients, enabling WSP to provide market-leading consulting services on some of the UK's most significant developments and projects."
WSP | Indigo was ranked as the fourth-largest consultancy in terms of chartered town planners in the 2019 Planning Consultancy Survey, and the sixth-largest for planning fee-earners.