A picture shows a Union flag, stickers and banners with slogans as campaign materials at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

An attendee holds up a banner at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

A picture shows Union flags, stickers and banners with slogans as campaign materials at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

An attendee has Union Flags in her hair at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

A picture shows hats, stickers and other campaign materials at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

A picture shows a Union flag, stickers and banners with slogans as campaign materials at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

A picture shows a Union flag, stickers and banners with slogans as campaign materials at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

An attendee has Union Flags in her hair at a political rally organised by the pro-Brexit Leave Means Leave group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Chairman of the pro-Brexit Leave Means Leave group, John Longworth, speaks at a political rally organised by Leave Means Leave in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Vice-chairman of the pro-Brexit Leave Means Leave group, Richard Tice, speaks at a political rally organised by Leave Means Leave in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Vice-chairman of the pro-Brexit Leave Means Leave group, Richard Tice, speaks at a political rally organised by Leave Means Leave in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Vice-chairman of the pro-Brexit Leave Means Leave group, Richard Tice, speaks at a political rally organised by Leave Means Leave in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

British Labour Party MP Kate Hoey speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

British Labour Party MP Kate Hoey speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Wetherspoon's Chairman Tim Martin speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Wetherspoon's Chairman Tim Martin speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Wetherspoon's Chairman Tim Martin speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Wetherspoon's Chairman Tim Martin speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

An attendee holds up a Union Flag at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Wetherspoon's Chairman Tim Martin speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Democratic Unionist Party (DUP) Sammy Wilson waves a Union Flag as he takes the floor to speak at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Democratic Unionist Party (DUP) Sammy Wilson holds up a printed copy of the Brexit Withdrawl Agreement as he speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

Democratic Unionist Party (DUP) Sammy Wilson waves a Union Flag as he stands to take the floor to speak at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)

British Labour Party MP Graham Stringer speaks at a political rally organised by the pro-Brexit Leave Means Leave campaign group in central London on December 14, 2018. - The Leave Means Leave group, supported by political figures like ERG chairman Jacob Rees-Mogg and former UKIP leader Nigel Farage, held a political rally to "Save Brexit" as the latest Brexit summit in Brussels leaves Theresa May facing a dwindling number of options over Britain's exit from the EU. The 27 leaders made abundantly clear to the British prime minister that the draft withdrawal agreement they reached after nearly two years of talks was not open to change. (Photo by Daniel LEAL-OLIVAS / AFP)