Tory former Cabinet minister John Gummer has launched a scathing attack on "extreme Brexiteers" over the Northern Ireland peace process.
Mr Gummer, who sits in the Lords as Lord Deben, accused them of trying to "ridicule the Good Friday agreement as if it didn't matter".
In debate on the European Union (Withdrawal) Bill, he bitterly criticised the "sheer vulgar partisanship" shown by some Brexit backing MPs and others outside Parliament.
To murmurs of support from across the House, Lord Deben said: "I've rarely been as angry as I was when I saw those extreme Brexiteers who tried to ridicule the Good Friday agreement as if it didn't matter.
"I say that as somebody who was in the Brighton bombing, whose wife was in the Brighton bomb, who had to help pick the things up afterwards."
Lord Deben said he did not accept "that these things should be treated with the sheer vulgar partisanship we have seen from some members of the House of Commons and elsewhere."
He was backing a move by some peers during the Bill's marathon committee stage to ensure animal welfare is safeguarded after leaving the EU.
Peers are seeking to revive an amendment, voted down by MPs sparking a social media backlash, that would transfer an EU protocol focused on recognising animals as sentient beings into UK law.
Ministers had previously argued the change risked creating legal confusion and that animal sentience was already recognised in UK law, primarily in the Animal Welfare Act 2006.
The Government has since published a draft Bill, enshrining animal sentience into UK law post-Brexit and introducing jail sentences of up to five years for animal abusers.
But Green Party peer Baroness Jones of Moulsecoomb was concerned this did not go far enough and argued the case for the original amendment, saying: "The Government's proposals are weaker than the EU law."
Remainer Lord Deben, a former environment secretary and agriculture minister, backing the move, said the animal sentience provisions were a "glaring" omission from the Bill, adding: "It's clearly missing and it ought to be there."
Citing the possible export of chlorinated chicken from the US, he said it was a fundamental issue not just of animal health but also the health of British people.
Warning about relying on ministers' "good faith" on future legislation, Lord Deben told cheering peers: "What the Government is asking us to do is not something the revising chamber should dream of doing. We should insist on this being changed."
Later, Tory former pensions minister Baroness Altmann backed a move to protect family friendly employment rights. gender equality and the work-life balance for carers and parents.
Lady Altmann said it was vital that existing protections were not lost and that Brexit "must not put women's progress and prosperity at risk or dilute parental and paternity rights".
As currently drafted the Bill did not provide sufficient protection for "hard won rights" and introduced the risk that rights would be weakened in future, she warned.
But Northern Ireland minister Lord Duncan of Springbank assured peers that all the rights already created would be brought back to the UK the day after Brexit.
He said there would be no "weakening or regression" of the rights, which could not be "undone" and would return to the UK and stand.