Lord Andrew Adonis announced his resignation as chair of the independent National Infrastructure Commission (NIC) last week.
His departure comes at a critical time for the NIC, which is due to unveil its first national infrastructure assessment (NIA) this summer. The deadline for responses to its initial vision and priorities document, published in October, expires on 18 January.
A spokesperson fro the NIC was unable to give any indication of the timescale for filling the position vacated by the outgoing chairman.
Adonis, a former policy adviser to Labour prime minister Tony Blair, served as transport secretary in 2009 and 2010. He was appointed chair of the NIC in 2015 and the position was reconfirmed in 2016.
In his resignation letter, Adonis paid tribute to the commission’s "good work", which he attributed to "dedicated public servants and commissioners". He added that deputy chair Sir John Armitt and chief executive Phil Graham "have been brilliant throughout".
He said he was "particularly proud" of the NIC’s plans for equipping the UK with fourth and fifth generation mobile systems, for Crossrail 2 in London and the High Speed 3 rail link for northern cities, and for "transformational" housing growth in the Oxford-Milton Keynes-Cambridge corridor, published in November.
"I hope these plans are implemented without delay," he added.
But Adonis said his work at the NIC had become "increasingly clouded" by disagreement with the government over the European Union Withdrawal Bill, which he described as "the worst legislation of my lifetime".
In any case, he said, he would have been obliged to resign from the commission following what he called transport secretary Chris Grayling’s "indefensible" decision to bail out the Stagecoach-Virgin East Coast rail franchise.