The welfare secretary brims with zeal. But the quiet man mostly stayed silent while the poor suffered. He makes noise now the chancellor is weak

Iain Duncan Smith brims with conviction when it comes to his own virtue. Having won the Conservative party leadership as a hard man of the right in 2001, on a visit to downtrodden Easterhouse in 2002 he made a very public embrace of compassionate conservatism.

In the years since, the zealous compassion of his rhetoric towards the vulnerable has been matched by the zealous conservatism of his actions. The two things were frequently in tension, and long before his explosive resignation as welfare secretary it seemed fair to ask whether one would eventually have to give.

But, somehow, in his own mind the bedroom taxes, benefit caps and endless freezes could always be squared with the personal mission he described in his parting missive to David Cameron – to “greatly improve the life chances of the most disadvantaged people in this country”. The same cognitive dissonance was at work in his decision to resign in protest over the budget cuts to personal independence payments (PIP), something he had acquiesced in when it was official policy, before walking out just as the government began to U-turn.

There were some successes in respect of both the work and the pensions parts of remit during his six-year stint, but cool appraisal does not suggest he deserves much direct credit. Strikingly strong employment growth during an otherwise anaemic recovery was a real plus. But it appears more rooted in the low-wage British way of business than benefit policy.

State pension simplification and the introduction of auto-enrolment also rank as successes, but both were driven by Mr Duncan Smith’s Liberal Democrat deputy Steve Webb, rather than with the boss. His unbending obsession was with benefits for people of working age.

Whatever the welfare question, Mr Duncan Smith always offered the same welfare answer: his universal credit scheme. There was an arguable case for tidying up various tax credits and payments into a single system, to reduce multiple form-filling and ease the deepest poverty traps that arise when several payments are simultaneously withdrawn.

The work and pensions secretary, however, never grasped that the most he could hope to do here was to rationalise the tricky trade-off between two inescapably competing objectives. On the one hand, relieving poverty among people who were not earning enough, and – on the other – encouraging them to earn more. And while over-hyping the theory, he neglected the practicalities.

Universal credit is years behind schedule. And even when – or should that be if? – it is fully up and running, the promised advantages will never materialise. Not least because, despite occasional tough talk before, Mr Duncan Smith allowed the chancellor to riddle his new creation with cuts, including those George Osborne backed off from making to the old tax credits, before it ever came into existence.

The Department for Work and Pensions acquired a wider reputation for incompetence. The work programme has disappointed, especially for disabled people. Brutal changes to employment and support allowance were botched so badly that a caseload, which had been drifting down for years, actually began growing again. In the sober summary from the National Audit Office, an embattled DWP “lacks understanding” of its own reforms and resources. Claimants of the benefit that PIP replaced, the very people whom Mr Duncan Smith resigns to defend, were previously at the sharp end of his maladministration. His 2012 overhaul was rammed through parliament in terms that were precise about the saving to be achieved, but so utterly hazy about how it was to be done that by 2013, in the face of chaos, the government slammed on the brakes.

Cuts that Mr Duncan Smith has signed off have produced a foodbank boom, have left tenants less secure and have impoverished children simply for being born into larger families. Previously rare punishment “sanctions” became common. People were left penniless for weeks on end. But the welfare secretary blithely insisted that most were grateful for the prompt to find a job.

The pressure of the deficit justified all sorts of horrors. But in resigning Mr Duncan Smith has pointed the finger, with devastating effectiveness, at the weakest point in the budget argument: the claim that PIP reductions for the vulnerable were unavoidable, when there were resources to cut taxes for the well-to-do.

On that point, at least, he has made a powerful stand. But in the light of record, it beggars belief that this was the sole consideration.

Walking out over a policy that was about to be dropped begins make more sense in the context of Mr Duncan’s Smith other obsession aside from universal credit – the European Union. Spotting a pro-EU chancellor with his back against the wall, the Europhobic welfare secretary saw his moment – and pounced.