In his resignation letter, the younger Johnson made no mention of his big brother who, let us never forget, is one of the chief reasons Britain is in such a hot mess with Brexit. It was unclear whether others would follow Johnson out of government.
But Mrs Thornberry said today that the option of campaigning for a second referendum was still on the table.
A government minister has quit with a stark warning over the impact on Kent of a no deal Brexit.
Prime Minister Theresa May this week faced pressure from her Westminster allies in the Democratic Unionist Party not to allow a customs border to split Northern Ireland from the United Kingdom after Brexit.
They have covered areas like aviation safety, civilian nuclear power, medical drugs, the rights of British citizens living in the European Union, road haulage and fishing rights.
Downing Street thanked him for his work but continued to insist there was no prospect of another referendum "under any circumstances". They're questions about the Northern Ireland border, they're questions about the kind of regulatory framework in which we'll live.
"This is the moment she has to face down Brussels and make it clear to them that they need to compromise, or we will leave without a deal", a senior cabinet minister told the Times.
As the United Kingdom continues to hurtle towards Brexit with no deal in place, plenty of leading voices are calling for the public to vote on the issue once again.
At the party conference, Labour delegates left open the possibility of backing a second referendum if it could not force a general election.
But she said she believed that another national vote on whether to leave the bloc would just give the same result, with the public asking: 'Didn't you hear us the first time?'
In a statement published on the Medium website, the younger Johnson claimed the Brexit deal the Prime Minister is pushing for would leave the United Kingdom "economically weakened, with no say in the European Union rules it must follow and years of uncertainty for business".
But even if she does get approval from her top team, there is growing concern that the Brexit deal will be voted down when it is put before MPs in December, according to a number of reports this weekend.
"Brexit has divided the country".
In marked contrast to his brother, who remains firm that leaving the European Union without a deal would be no bad thing, and resigned because he believed the deal being negotiated was too soft, Mr. Jo Johnson called for a second referendum.
Transport Minister Jo Johnson has stepped down to protest UK Prime Minister Theresa May's Brexit plan.