With anger growing over the controversial Chequers plan which will leave Britain “half in, half out” of the EU, the Bow Group and Bruges Group have organised a conference on 1 and 2 October.
In a further blow to the Conservative leadership, the Brexit conference at the Birmingham Midland Institute will hear from leading Tories including former cabinet ministers Priti Patel, John Redwood and Owen Paterson.
There will also be speeches by senior Tory MEP and trade expert David Campbell Bannerman and Andrea Jenkyns, the Tory MP who has openly been collecting signatures to hold a vote of confidence in Mrs May’s leadership.
Respected pro-Brexit Tory MPs Daniel Kawcynski and Sir Bill Cash will also make speeches and share a platform with former Ukip MEP Steven Woolfe who has been controversially blocked from joining the Conservatives.
The chairman of the Bow Group Ben Harris-Quinney told the Daily Express: “The Bow Group has boycotted Conservative Party Conference since 2013 in protest of the lack of Party democracy.
“Things have since gotten worse and the Conservatives are unable to explain their membership policy which excludes strong Brexiteer conservatives like Steven Woolfe but welcomes Remainers, liberals and socialists.”
He said that the conference was the first event for the Brexit Advance Coalition of 10 organisations which have come together to fight back against the Chequers plan.
Mr Harris-Quinney went on: “We are proud to have formed the Brexit Advance Coalition with ten other like minded organisations and look forward to inaugurating with this fantastic programme of events and speakers in an alternative conference in Birmingham in the first days of October.
“Time is short, we need to ensure that a full Brexit is enacted by March and a Brexiteer conservative government is able to lead Britain forward into a new era.
“Unlike the Conservative Party Conference all are welcome at our conference, and we look forward to also welcoming representatives from Leave means Leave, Stand up for Brexit and the European Research Group [of Tory pro-Brexit MPs] and working with all Brexit supporting groups towards that cause.”
The announcement comes as Ms Patel has launched a fresh attack on the Chequers compromise and demanded that Theresa May stops the Project Fear being orchestrated by the “pro-Remain Treasury” to scare people over a World Trade Deal option with no formal deal with the EU.
In a column in The Sunday Telegraph, Ms Patel, who served as Secretary of State for International Development from 2016 to 2017 and was a key member of Vote Leave, called on Prime Minister Theresa May’s administration to “believe in Britain and the tremendous opportunities that lie ahead.”
She added: “Our friends at the Treasury have doubled up, and co-opted Mark Carney, governor of the Bank of England, to bolster this message with wild predictions that house prices will fall by a third – while interest rates will soar.”
Brexiteer Ms Patel, who campaigned for Leave during the referendum, described the doomsday proclamations as “laughable”, and an “extreme scenario” which was in fact part of the 2017 Bank of England stress test aimed at assessing whether banks could cope with a massive financial shock.
She added: “To present this as the most likely scenario for a no deal Brexit amounts to irresponsible scaremongering that is untrue.”
Ms Patel sought to remind Mrs May of her responsibility to “deliver a better future” and stand by the referendum result.