Current managing director of the group’s natural resources division Alex Vaughan will be appointed as CEO with effect from the conclusion of the company’s AGM on May 7.

Mr Wyllie said he is retiring in order to pursue a non-executive career. He recently took up the presidency of the Institution of Civil Engineers and is a non-executive director of Yorkshire Water Services.

Costain said the appointment of Alex Vaughan is in accordance with the Board’s succession plan which included an extensive internal and external search process.

Mr Vaughan joined Costain in 1992, was appointed to the executive Board in 2006 and has played a leading role in the firm’s transformation into a smart infrastructure solutions business through his leadership of the development and growth of the group’s consultancy and technology services.

In his current role, Alex has delivered significant growth in profit and margin in the natural resources division.

He is a qualified chartered quantity surveyor, has worked on infrastructure projects in the UK and internationally and, additionally at Costain, has held various corporate roles across HR, strategy, M&A and corporate development.

In order to effect an orderly handover, Andrew will remain as CEO and on the Board until May 7 and will remain an employee of the company until September 6.

Dr Paul Golby CBE, chair, said: “I would like to thank Andrew for everything that he has done for the business and to wish him and his family well for the future. Andrew can feel extremely proud of what he has achieved at Costain.

“He leaves the group in good health, the result of the growth strategy which he and his colleagues have been implementing for the last fourteen years. We are delighted that Alex will be taking over. He has played a major role in the development of the group and the implementation of its strategy, and has the expertise and ambition to deliver the future growth of the business.”

Andrew Wyllie CBE, said: “I have thoroughly enjoyed the past fourteen years and would like to thank my colleagues for their support and commitment. Costain is a great business with a great future ahead of it.”

Alex Vaughan added: “I am delighted to have been appointed CEO and very much look forward to leading the business and continuing our strategy as we enter a new era of opportunity for Costain.”

Costain also posted its annual results for 2018 today, showing a 4% dip in pre-tax profit and a 14% revenue slide.

Revenue, including share of joint ventures and associates, was down 14% to £1,489.3m (2017: £1,728.9m) reflecting a lower level of capital project activity in the year.

Reported profit before tax for the year was £40.2m (2017: £41.8m). However, stripping out one of costs such as an £8.6m pension charge and £3m amortisation of acquired assets, underlying operating profit was up 7% to £52.5m (2017: £49.1m).

Andrew Wyllie CBE said: “The Fourth Industrial Revolution is now having a global impact and is characterised by a fusion of technology breakthroughs that are blurring the lines between the physical, digital and biological spheres.

“These breakthroughs are occurring in a number of fields including artificial intelligence, robotics, nanotechnology, quantum computing and biotechnology.

“We are therefore seeing a rapid change in the spending patterns of our clients, with the deployment of emerging technology being core to their next generation of infrastructure solutions.

“We are strategically positioning Costain at the forefront of this revolution, transforming the business into a leading smart infrastructure solutions company.

“This differentiation is allowing us to seize the wide array of exciting opportunities being created for our business.

“Our considerable expertise across the integration of technology, consultancy, asset optimisation and complex delivery services places Costain well in this rapidly-evolving market.”