Sector commentators are dismayed by the Labour peer’s decision, which was made over the Government’s plan to amend the Stagecoach / Virgin rail franchise from the East Coast mainline and its handling of Britain’s withdrawal from the European Union.

Observers say that Lord Adonis was respected for his work from across the political spectrum and that finding a suitable replacement as chair of the commission will not be easy. But others point out that Lord Adonis set in motion a long term approach to infrastructure thinking which can be taken forward by others.

Think tank the Institute for Government’s associate director Nick Davies told TP Weekly News: “Lord Adonis is clearly a transport enthusiast, with a particular interest in rail, and was one of the key intellectual architects of the Commission’s work. It is important to get a new chair in place relatively quickly.”

He added that the nine remaining commissioners have a huge amount of experience, but lack diversity in terms of their backgrounds, and the Commission could benefit from a chair who is based outside of London and the South East.

Another leading transport figure, who asked to remain anonymous, said: “Andrew Adonis is respected among all of the main political parties and provided a huge amount of strength to the work of the Commission. It is sad to see him go, and it will be difficult to find someone with his experience and ability to come in as chair and take away the political heat from the infrastructure debate.”

CIHT Vice President Martin Tugwell said: “Under his stewardship of the National Infrastructure Commission, we have seen the added value that long term strategic planning has to play in shaping our future. CIHT continues to be an advocate of the critical importance of strategic transport planning being at the heart of shaping the future of our society.  

“As Lord Adonis has demonstrated, strategic leadership needs to be central to shaping the UK’s investment in infrastructure and services; through the CIHT we will continue to make that case.”

Former Transport Minister and infrastructure specialist Steve Norris FCIHT commented: “I have a lot of time for Andrew Adonis. He has experience of cabinet Government and of dealing with major projects which is equalled by very few in the UK, so I am sorry to see him go.”

But he added: “Fortunately the Commission has in the presence of its Deputy Chairman Sir John Armitt a man who was not only the originator of the NIC concept but who acted as Chairman for a short period last year. So I am confident that the work of the NIC will continue and that the quality of its offerings will be maintained.”

In his resignation letter to the Prime Minister, Lord Adonis said that he is proud of the Commission’s work on developing Crossrail 2 in London, High Speed 3 in the north and for promoting housing growth along the Oxford – Milton Keynes – Cambridge corridor.

“I hope these plans are implemented without delay,” Lord Adonis wrote. “However, my work at the Commission has become increasingly clouded by disagreement with the Government, and after much consideration I am writing to resign because of fundamental differences which simply cannot be bridged.”

He described the European Union Withdrawal Bill as “the worst legislation of my lifetime” and said the decision to ‘bail out’ the Stagecoach / Virgin East Coast rail franchise is “indefensible” as it will “cost taxpayers hundreds of millions of pounds, possibly billions if other loss making rail companies demand equal treatment”.

Lord Adonis added that he needs “to be free to set out serious public interest concerns” regarding the East Coast franchise when it inevitably comes under close scrutiny.

The Department for Transport responded by saying: “No one is getting a bailout and Virgin Stagecoach will continue to meet its financial commitments made to the taxpayer on the East Coast rail franchise.”

A spokesman for the National Infrastructure Commission said it “cannot comment at the moment” as to when a successor to Lord Adonis will be named. A Treasury spokesman added: “We thank Lord Adonis for his service. The Government looks forward to appointing his successor.”