At first glance, the amendment to the EU (Notification of Withdrawal) Bill in the House of Lords giving Parliament a "meaningful vote" on a Brexit deal may look innocuous.
The Lords have already scuppered the UK Government's plans for Brexit, by adding an amendment to the bill now going through parliament, demanding the government give an undertaking - within three months of triggering Brexit - to protect the rights of European Union workers in the UK.
Challenged by Tory peers that this would provide no incentive for the EU to give the United Kingdom a good deal, Lord Newby said our European partners would negotiate in "good faith" and branded such an "unfriendly" view as "deeply depressing".
With the Prime Minister vowing to trigger Article 50 before the end of March, senior peers now expect ping pong on Monday 13 March, with the Lords amendments being debated - and thrown out - by MPs in the Commons in the afternoon.
The government has vowed to fight any changes to the legislation before they become law when the bill is presented for approval to the lower chamber, where May has a small majority, next week.
He said: "It is disappointing that the House of Lords has chosen to make further changes to a Bill that the Commons passed without amendment". When representatives of British people who were living overseas came to appear before the committee, you might have thought, Andrew, they would say look don't guarantee the rights of the European Union citizens here until you've secured our position, but that is not what they said. Earlier, the peers voted against putting the outcome to a second referendum.
The government is in more danger of losing a second vote in the House of Lords later on Tuesday on the issue of forcing May to hold a more meaningful parliamentary vote on Brexit.
Independent crossbencher Lord Pannick QC said British Prime Minister Theresa May had accepted the need to give Parliament a vote on the terms negotiated.
The Brexit bill will now return to the elected House of Commons with the amendment forcing May to have a vote on her Brexit deal and another guaranteeing the rights of European Union citizens.
It has also seen the once-great sterling plumb embarrassing depths against a raft of other currencies, sending inflation higher and hurting the disposable income of ordinary working people.
Lord Turner of Ecchinswell, a former chairman of the Financial Services Authority, said: "Any idea that the vote of last June reflects the will of the people in some unanimous, all the people together, Una Voce, unanimous, absolute and forever unchanging fashion is. not democratic, but the Brezhnev Doctrine". This would mean that the Prime Minister will be able to invoke Article 50 immediately after that.