The multi-professional consultant said the deal to acquire Indigo Planning, which employs around 90 staff out of offices across the country, would be completed next month.

WSP has recently grown its planning team with a series of senior hires.

Mark Naysmith, UK CEO of WSP, said: “With the collective expertise of WSP and Indigo’s planning specialists we will become one of the UK’s largest planning consultancies, operating in the infrastructure, property, energy and environmental markets.

“Our newly combined skills will increase the strength and diversity of our service offer for our clients across the UK.”

Indigo Planning’s chief executive, Simon Neate, said: “This move represents the next phase in Indigo Planning’s evolution and will create new and bigger opportunities for both our colleagues and our clients in the UK and internationally.”

Founded over 30 years ago, Indigo is a specialist town planning consultant, providing specialist planning advice on residential, retail, commercial, industrial, leisure, tourism, infrastructure, energy and regeneration among others.