It was an uncomfortable experience reading today’s Work and Pensions Committee report on what we are now calling the “social sector size criteria” – aka the bedroom tax – and other components of housing support affected by welfare reform.

It was uncomfortable because the cross-party Committee highlights the diverse negative impacts beginning to be documented, a year on from a tranche of major changes to the welfare system.

It is a story of households who are unable to move, because there isn’t suitable alternative accommodation, being plunged into greater poverty.

It is a story of households who do move finding themselves in poorer quality and more insecure accommodation.

It is a story of self-defeating rules that save money under one heading only to incur it again under another.

It is a story of households already facing huge challenges – such as coping with severe disability – being caused further distress by being required to rely upon the vagaries of discretionary housing payments.

After all, it is hard to think of a better way of saying that we, as a society, care than keeping households facing long-term limiting illness or disability in a state of perpetual anxiety. We need to subject them to the hassle of repeatedly petitioning their local authority for the small sliver of available resources necessary to keep the roof over their heads. We wouldn’t want to grant them assistance as of right. Oh no. You never know, they may not need that dialysis machine next year. We might pause to celebrate their miraculous recovery. We must certainly stop them hoarding that spare room they had been keeping the machine in.

Reading the report was also an uncomfortable experience because it engendered a sense of deep frustration. I don’t think there was anything in the Committee’s report that hadn’t been forecast as a likely consequence of the policy by those who understand something about housing markets and the welfare system. All the main criticisms of the policy made since it was first proposed appear to be being borne out in practice. In other circumstances that might be a cause for schadenfreude. But in this case it is a genuine tragedy.

Given its failure to meet its stated objective, while not saving any money but imposing considerable human cost, my belief grows by the day that the bedroom tax will be added to the canon of great British policy blunders. Whether its days are numbered is a different matter. Despite its manifest failings it remains a popular policy with those who aren’t directly affected by it.

The day’s other bedroom tax-related development was Tim Farron’s speech against the policy. It’s been suggested that this speech signals something about the tussle within the Liberal Democrats over the content of the 2015 manifesto. Be that as it may, it is a speech that was met with widespread derision in Labour quarters. How can the Liberal Democrats come out against a policy that they were instrumental in voting into law?

One Labour website today provided a handy list of all the opportunities both Nick Clegg and Tim Farron had to vote against the bedroom tax if they didn’t like it. But, the author helpfully went on to point out, these leading Lib Dems generally failed to do so.

We could write Labour’s criticisms off as yet another example of a failure to understand the nature of coalition and be done with it. But I think in this case there is more to say.

Because there has been plenty of criticism of the bedroom tax from within the Lib Dem ranks before, during and after its passage into law. Some us pointed out that it was not going to deliver and it was very likely to have serious negative consequences. Liberal Democrat Conference has passed critical motions relevant to the topic on more than one occasion. Yet these concerns were largely ignored by the leadership. A small boost to the discretionary housing payments fund was undoubtedly welcome. But it is a sticking plaster not a solution.

Of course, we could say that this just illustrates that the Liberal Democrat grassroots don’t understand coalition either and be done with it. If so then it would appear that the Liberal Democrat leadership are the only ones blessed with this esoteric knowledge. But I think in this case there is more to say.

We could argue that Tim Farron is doing no more than, belatedly, giving voice to the sorts of concerns that have been expressed by many at the grassroots – and that his hand has been strengthened by the emerging evidence on the social costs of the policy. Maybe he didn’t like the bedroom tax all along and up until now was compelled to support welfare reform by a higher authority. And the powers of that higher authority are now fading. Maybe he supported the policy previously, even in the face of the concerns being expressed about it, but has now seen the light. Who knows? Not me, for sure.

But I do feel that the Liberal Democrats are on shaky ground here. As a party that ostensibly values evidence-based and rational policy making, it nonetheless supported a measure into law that experts in the field were almost unanimous in expressed grave concerns about. And now it appears the party is deciding that this may have been a bad idea, for all the reasons that it was warned about in the first place.

If the party leadership has never been persuaded of the wisdom of the bedroom tax then it gives us yet another indication of the price it was willing for others to pay to hold the Coalition together. Or it indicates the limited amount of leverage the party was able to exert over the welfare reform agenda.

For the avoidance of doubt, I am glad that Tim Farron has come out against this policy in its current form. I have always thought it was little more than vindictive. That much may have been reasonably clear from my previous posts on the topic. I would have preferred the party to stand against it from the outset. But maybe that is just another example of my failure to understand the nature of coalition government.

It is, nonetheless, hardly surprising that the party’s opponents will seek to make political capital out of these inconsistencies and inadequacies. They continue to see this as fertile terrain on which to cause maximum damage in the political game.