Prime Minister Boris Johnson has given the clearest indication yet that he envisages the UK diverging from EU environmental rules post-Brexit, declaring that the ability to introduce laws and regulations that differ from the EU "is the point of our exit".

In a letter to EU Council President Donald Tusk ahead of a series of meetings with EU leaders this week, Johnson last night set out his vision for a how a new Withdrawal Agreement that removes the so-called Irish Backstop could be finalised before the UK's planned exit from the EU on October 31st.

Making no reference to Johnson's previous vote in favour of the Withdrawal Agreement brokered by Theresa May's government, the Prime Minister argues commitments to ensure Northern Ireland remains in "full alignment" with the bulk of Single Market and Customs Union rules if "alternative arrangements" for managing the Irish border fail to materialise are "anti-democratic".

"The Treaty provides no sovereign means of exiting unilaterally and affords the people of Northern Ireland no influence over the legislation which applies to them," he writes.

He also argues that continued EU control over regulations in part of the UK runs counter to the government's Brexit ambitions, specifically referencing the desire for the UK to have the freedom to set its own environmental laws and regulations.

"[The backstop] is inconsistent with the UK's desired final destination for a sustainable long-term relationship with the EU," Johnson writes. "When the UK leaves the EU and after any transition period, we will leave the single market and the customs union. Although we will remain committed to world-class environment, product and labour standards, the laws and regulations to deliver them will potentially diverge from those of the EU. That is the point of our exit and our ability to enable this is central to our future democracy."

The letter stresses the UK remains committed to the Good Friday Agreement, finding a way to avoid the return of a hard border, and on-going North-South cooperation on the island of Ireland, including through the Single Electricity Market.

But while Johnson insists leaving the EU with a deal is the government's "highest priority", he also reiterates that "the backdrop cannot form part of an agreed Withdrawal Agreement".

He instead argues "flexible and creative solutions" need to be developed to avoid a hard Irish border before the end of the planned two year transition period.

The EU has repeatedly stressed it will not drop the backstop, arguing it is essential to the integrity of the European single market should alternative mechanisms for avoiding a hard border between Ireland and Northern Ireland fail.

It has also signalled that relatively close levels of on-going environmental co-operation will be critical if the UK is to secure a comprehensive trade deal with the bloc.

The previous Withdrawal Agreement brokered with Theresa May's government left open the possibility of some divergence on environmental regulations, but contained firm commitments to maintaining alignment in terms of environmental outcomes.

Specifically it included a section on "non-regression in the level of environmental protection", which included a series of commitments designed to ensure the UK and EU's environmental and climate policies remain broadly aligned on a raft of issues.

It stated that in order to ensure "the proper functioning of the single customs territory", the EU and UK "shall ensure that the level of environmental protection provided by law, regulations and practices is not reduced below the level provided by the common standards applicable within the Union and the United Kingdom at the end of the transition period."

It also stressed that the commitment covered the continued adherence to EU environmental principles and almost the entire gamut of existing green rules and targets.

In addition, the Political Statement agreed by the May government that was meant to provide the basis for a future trade deal pledged to maintain co-operation around "areas of climate change, sustainable development, cross-border pollution, trade protectionism and financial stability" and reaffirms the UK and EU's commitment to international environmental treaties, specifically referencing the Paris Agreement.

May subsequently moved to strengthen the UK's post-Brexit environmental safeguards further, announcing plans for new legislation to give Parliament a say in whether rules should diverge and launching a major new Environment Bill designed to introduce new governance measures.  

It remains unclear if Johnson's commitment to maintaining "world-class" environmental standards would see the government sign up to an agreement that broadly mirrors May's adherence to EU environmental goals or whether he will seek changes that would make it easier for the UK to diverge from existing environmental rules.

Ministers were quick this morning to again reiterate the government's support for high environmental standards post-Brexit.

Writing on Twitter, Environment Minister Therese Coffey rejected interpretations of Johnson's letter that suggested it meant the UK will definitely diverge from EU environmental regulations, arguing that it "reinforces that our Parliament(s) will decide the regulations and they may differ from what the EU decides to do in the future".

However, Johnson has in the past repeatedly argued that one of the benefits of Brexit would be the freedom to diverge from EU rules that he does not feel are suitable for the UK, citing restrictive planning or farming rules.

In a speech last year that was widely criticised by environmental campaigners, Johnson made the case for scrapping some EU green rules.

"We can simplify planning, speed up public procurement, and then perhaps we will then be faster in building the homes that young people need," he said at the time. "We might decide, we might, that it was absolutely necessary for every environmental impact assessment to monitor two life cycles of the snail or build special swimming pools for newts, not all of which they use in my experience. But it would at least be our decision to do that."

He also hinted the UK should have the freedom to diverge from energy efficiency rules if it wanted to. "It is all about voluntarism," he said. "It is all about who decides. When it comes to EU standards for washing machines or hairdryers or vacuum cleaners or whatever, it may very well make sense to remain in alignment as a matter of choice. As something we elect to do. I am sure for the purposes of supply chains there are many businesses who understand the need for that. But I don't think we should commit as a matter of treaty that forever and a day we are going to remain locked into permanent congruence with the EU."

Speaking at the time, Shaun Spiers of the Greener UK group of NGOs, said: "Anyone who has concerns about the environment sees continued high standards for UK as critical, and this speech seemed to set out a vision that was quite the opposite to that. As for the tired old gag about newts - we can do better than that."

Consequently, the latest developments will spark further concerns amongst green businesses and campaigners who are already worried that a no deal Brexit could result in both an economic crisis and huge uncertainty over the future of UK environmental governance and regulation.

Many businesses fear that any significant divergence from EU environmental regulations could create a costly patchwork of rules and regulations, while also potentially making it easier for future governments to water down environmental policies and protections.