Parliament is finalising laws that will formally end Britain's membership of the European Union, a process which has forced the government to make some important concessions that will change the dynamic of Brexit negotiations.
The strained parliamentary session underlined deep divisions over Britain's European Union exit.
The government has always promised to give lawmakers a vote on the final exit deal it negotiates with the EU. By 2pm the only speeches had been from the two main frontbench spokesmen (Brexit minister, David Davis, and Labour's Matthew Pennycook).
The Lords amendment would have given parliament the power to decide what happened next, with the possibility of reopening negotiations or staying in the bloc.
"It's not practical, it's not desirable and it's not appropriate", he said.
He said: "I understand the difficulties MPs representing constituencies which voted strongly for Leave or Remain have on the EEA amendment to the EU Withdrawal Bill".
Brexit backers see this clause as weakening the government's negotiating position, as they want May to be able to threaten to walk away.
Adding pressure on Theresa May's government, her junior Minister of Justice, Philip Lee, submitted his resignation, making clear that he was prepared to abstain rather than support his government's position against the amendment.
It followed a strained parliamentary session, where the deep nationwide divisions opened up by Britain's vote to leave the European Union in 2016 were on display, with pro-EU lawmakers saying they had received death threats.
"Secondly, we can not change the fundamental constitutional structure which makes the Government responsible for global relations and worldwide treaties".
Also on Tuesday, the government successfully overturned an attempt to remove the date of Brexit from the face of the bill.
The Prime Minister appears to have rowed back on promises to rebel MPs yesterday that she would discuss another concession with them this week.
Grieve praised the government for addressing their concerns after the vote.
Another flashpoint could come when lawmakers vote Wednesday on an amendment seeking to keep Britain in a customs union with the EU.
Or possibly not. That's when we will find out just how many Tory "Remainer rebels" really do mean business on Brexit, as the Commons votes on whether to force the Government to hold a "meaningful vote" on the Theresa May's final deal.
Her minority Conservative government relies on the support of Northern Ireland's Democratic Unionist Party for a slender working majority in the 650-member Commons.
The main point of contention between those who want to keep the closest possible ties with the European Union and those who aim for a clean break is a demand to give parliament a "meaningful vote" on any agreement that May negotiates with Brussels.
Parliamentary debates about complex legal amendments rarely rose much heat, but passions run high over anything to do with Brexit.
Britain's highest-selling tabloid, The Sun, which is owned by Rupert Murdoch, addressed lawmakers directly on its front page, saying they faced a choice between "Great Britain or Great Betrayal".
It featured a British flag and the headline: "Ignore the will of the people at your peril".
Heidi Allen was one of the 14 Tory rebels who struck a deal with the Prime Minister last night in order to back the EU Withdrawal Bill in parliament last night.
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