Environmental campaigner Chris Packham has filed his legal challenge to the Prime Minister’s go-ahead for the £100bn-plus rail project, HS2.

Mr Packham has applied to the High Court for permission for judicial review of the PM and Transport Secretary’s decision to give the go-ahead for the vast project.

Mr Packham has also requested the court to grant an urgent interim injunction to halt all clearance and construction works, which he claims will cause irreversible and irreparable loss of designated ancient woodlands and disturb European Protected Species and nesting birds, until after his legal challenge has been determined.

Mr Packham, who is represented by law firm Leigh Day, argues that the decision to allow HS2 to proceed is unlawful because it was made on the basis of the findings and recommendations of the Oakervee Review.

Mr Packham is concerned that the review was fundamentally flawed in failing to provide an independent, impartial and rigorous appraisal of relevant environmental and climate change factors.

Mr Packham’s claim that the Oakervee Review deviated from its own terms of reference is supported by witness evidence from the Deputy Chair of the Oakervee Review, Lord Berkeley, who resigned from the Review Panel on the basis of concerns over how the review was operating and subsequently published his own dissenting review of HS2.

Lord Berkeley claims that instead of a wholly panel based approach, the review was led mainly by the Chair, Doug Oakervee, with input from civil servants from the Department of Transport. He was excluded from key meetings and he and other panellists were unable to review together the full range of evidence submitted to the Review – and in fact were unaware of much of it.

Mr Packham is also arguing that the consideration of environmental matters was not rigorous and gave a misleading picture as to the scale and significant of impacts.

He says the review failed to consider submissions highlighting concerns about the impact of tunnelling on the chalk aquifer with possible impacts on water flow in the River Misbourne and drinking water quality in the Chilterns, Shardeloes Lake or internationally important chalk streams.

In his legal case he argues that the report’s assessment of HS2’s impact on the climate was similarly flawed, including its analysis of the achievement the Net Zero 2050 target and the UK’s obligations under the Paris Agreement – all at a time of a declared climate and environmental emergency.

Mr Packham argues that the government would have assumed the Oakervee Report was the product of an independent and impartial process and that all submissions, including those of the RSPB, the Chilterns Society, the Woodlands Trust and the Chilterns Conservation Board, would have been taken into account in reaching a view to proceed.

However, he says it is now "clear" that this was not the case.

Mr Packham said: “We are in a time of grave national and international crisis and our government is under considerable pressure. I wholly sympathise with that and respect the need to support their urgent priorities.

"Beyond this critical and worrying period lies another - our species’ continued tenure on planet earth.

"To survive beyond coronavirus we will need a healthy and sustainable environment so we must continue to ensure that is what we will inherit.

"HS2 is wholly incompatible with this longer-term, and fundamentally necessary, aim.

"The Oakervee Review was compromised, incomplete and significantly flawed in regard to its environmental considerations. Indeed, its very process was far from independent and impartial.

"And yet the government made its decision to progress with this project based upon this report.

"Given that the UK is a signatory to the Paris Climate Agreement, and that it has declared a ‘Climate and Environment Emergency’, I believe that this decision was plain wrong.

"The cost on the ground to rare wildlife, endangered habitats and important green spaces is profound.

"The carbon cost is unacceptable and fundamentally incompatible with our necessary Net Zero obligations.

"The cost to the public purse , which is about to rupture due to the current catastrophe, both human and economic, is absurd. We must stop HS2 as soon as possible - for all life on earth.”

Mr Packham is being represented by Tom Short and Carol Day from law firm Leigh Day.