Three Scots Tories are among the signatories to a letter from pro-Brexit MPs calling on the United Kingdom to make a clean break from the European Union.
The group is headed by leading Brexiteer Jacob Rees-Mogg.
That the United Kingdom has "full regulatory autonomy" and isn't constrained by European Union rules after-Brexit - which would be a possible outcome if the government successfully pushes for a close relationship with the organisation.
The letter included a series of suggestions for Theresa May, such as asking for "full regulatory autonomy"; only complying with the EU's vision for a transition period "if the final deal is fully negotiated"; and make sure the United Kingdom can negotiate trade deals with "third countries" as soon as it leaves the EU.
The members of the European Research Group are pushing for a clean break from the EU with "full regulatory autonomy" outside of the European Single Market.
MPs offered "some suggestions" on how a free-trading, global Britain could be achieved - by "taking control of our tariff schedules at the WTO", and ensuring the government can change British laws and rules after Brexit, as opposed to being "a rule taker".
MPs said the United Kingdom should negotiate as an equal partner in the proceedings.
'The UK should negotiate as an equal partner.
The letter was signed by Dumfries and Galloway MP Alister Jack, Stirling MP Stephen Kerr and Gordon MP Colin Clark - but not by Aberdeen South MP Ross Thomson, who was a spokesman for the Vote Leave campaign in Scotland.
It also states that the transitional phase-or implementation period-that's now being negotiated must meet their own criteria and be based on World Trade Organization principles.
With no majority, she knows that she needs to keep the dozens and dozens of Brexit-backing Tory MPs broadly with her for her own government's survival.
May has faced criticism from colleagues who say she lacks vision, while Brexit supporters fear she'll sell them short and tie Britain too closely to European Union rules.
"It is clear from this list of demands that the Tories don't want either a transition deal or a future relationship with the EU".
A "Ransom Note" demanding Hard Brexit comes as the Prime Minister and "Soft Brexiteers" have been hoping to reach accommodation with Brussels.