"Are the unemployed to be treated as criminals?" he said of the Jobseekers Allowance. "What will it do to the morale of our society to proceed in this way? ... What will it do to the public service ethos to create arbitrary powers, systematically encourage officials to disqualify from benefit, sanction claimants even more severely than at present?" he asked.
"Is it to appease the consciences of the affluent so that they can feel more comfortable, believing that those who are poor are feckless and fiddling the system?"
No wonder he was under suspicion for months from government whips as likely to jump ship. Trying to engage the Prime Minister in a debate about the Bill was like "spitting in the wind", he told BBC Television's Breakfast with Frost, yesterday. The upshot of his frustrations could make moves to put "clear water" between an ever more rightwards-leaning Tory Party and Labour even more explosive than before.
Mr Howarth's friends on the "wet" wing of the Tory party had been feeling disillusioned for months. They fear John Major is being drawn closer to the right wing to ensure its support.
No one else was prepared to follow Mr Howarth yesterday, but his departure could signal an intensification in the battle for the soul of the Tory Party, with the centre-left fearing the Tory leadership will revert to a Thatcherite agenda of cuts in the welfare state to pay for tax cuts as a pre-election bribe.
The probability of further defections - perhaps to the Liberal Democrats - remains small. But that is arguably of limited consolation to a Prime Minister who thought he had reunified his party. Droves of sitting Tory MPs are voting embarrassingly with their feet by announcing they will not contest the next election, including thoughtful minds such as former minister George Walden, the MP for Buckingham.
The fears of a right-wing party coup by Mr Portillo, now Secretary of State for Defence, were eased by the leadership contest, which secured Mr Major's position. The appointment of Michael Heseltine as Deputy Prime Minister appeared to put the left of the party in the ascendancy. But Mr Howarth yesterday described Mr Major's victory as "hollow". "There's a kind of listlessness, there is a lack of vision, a lack of clear determination as to where the Conservative Party should go."
Another left-of-centre MP said: "It settled Mr Major's position, but the drift to the right is inexorable."
Many on the left, such as Peter Temple-Morris, MP for Leominster, are supporters of Mr Heseltine, who voted for Mr Major to stop the right-wing challenger, John Redwood.
The defection has raised fresh misgivings about the direction of the party. The Macleod group and the Lollards, run by Mr Temple-Morris, have proved incapable of organising to stop the Thatcherite 92 Group, run by Sir George Gardiner, MP for Reigate, seizing control of most of the backbench committees.
The Tory left tends to be the older generation and are being replaced by Thatcherites, such as Gerald Howarth, who is standing in Aldershot, the seat held by Mr Heseltine's biographer, Julian Critchley.
While the Tory left believes Mr Howarth has gone too far, losing them a standard-bearer, some were predicting a realignment of the Tory Party if John Major loses the next election. Many would refuse to continue in a right-wing Tory party under Mr Portillo. And some are prepared to join the Liberal Democrats after the election - the leap to Labour would be too great. "The Tory Party is an uncomfortable place for us at the moment. The sooner there is an election the better," one unhappy Tory said.
A degree of unhappiness will undoubtedly be the future lot of Mr Howarth. But the sheer inevitability of it all was becoming plain to see. Mr Howarth was the sole Tory MP invited to the February launch of The State We're In, the best-selling book by Will Hutton, post-Keynesian guru of left- of-centre economics. Mr Howarth, whose invocations of Burke and Disraeli are legion, grinned when asked what he was doing in the Tory Party. Later, when Mr Portillo was suggesting Britain should leave the International Labour Organisation, he instantly signed up to Labour MP Denis MacShane's Early Day Motion deploring the move.