The House of Lords broke no constitutional conventions in referring back Osborne’s vindictive tax credit cuts. The Tories and their media supporters are talking utter garbage on the question. Taking Britain’s appalling “constitution” for what it is, the arcane rules of procedure were not breached.

Ever since David Lloyd George and Herbert Asquith forced, by threat of massive creation of peerages, the 1911 Budget through and with it the start of National Insurance and the demise of the workhouse, there has been a convention that the Lords do not oppose or amend Finance Bills.

But the tax credit cuts were not in a Finance Bill. Osborne instead tried to sneak them through by statutory instrument. This is secondary legislation whereby a Minister signs off laws under powers delegated to him by primary legislation. Secondary legislation gets much less parliamentary time and committee scrutiny. If Osborne had put the tax credit proposals in a Finance Bill, as they certainly should have been – it is Osborne who was breaking parliamentary convention here – rather than sneak them under the table as secondary legislation, the Lords would indeed not have been able to stop them without breaching constitutional convention. Which just goes to show it doesn’t always pay to be a weasel.

Osborne is hoist by his own petard.

Aah, Tories say. But there is another convention that the Lords do not block secondary legislation.

They are making that one up. There is no such constitutional convention and there are plenty of examples of the Lords blocking secondary legislation. There is a huge quantity of secondary legislation, thousands and thousands of laws – ministers continually are signing off legal changes.

But the entire basis of the secondary legislation is that parliament has delegated to ministers, in Acts, powers to sign off uncontroversial matter. This can be, for example, the detail of regulations needed technically to enforce primary legislation, and the occasional updates needed. Only a very low percentage indeed of secondary legislation ever gets queried by the Lords, but that is not because of a constitutional convention. That is because most of it is dull stuff. But when the government abuses its authority and tries to smuggle vital changes through secondary legislation, the Lords not only has the constitutional right to challenge this abuse, it has the constitutional duty to do so.

I wish they would do it more often. For example, when the Labour Party used Westminster secondary legislation to cede 6,000 square miles of Scotland’s sea to England without parliamentary scrutiny.

Finally, there is a constitutional convention that the Lords do not oppose manifesto commitments on which a government has been elected. But the Tories rather carefully did not put tax credit cuts in their manifesto, and indeed in campaigning said they would not do it.

The British constitution is appallingly undemocratic. The fact that an undemocratic chamber has fended off a proposal from an undemocratic executive which gained the votes of only 37% of the voting electors, is not a blow struck for democracy. It is however a temporary victory for human decency in mitigating an attack on the poor.

It is also an achievement for Jeremy Corbyn. Nobody can truly believe that Labour peers would have been organised to do this under Yvette Cooper or Liz Kendall.

UPDATE Wings Over Scotland has a very different take on the Labour Party performance. That the Labour Party was not radical enough to go for the “fatal” option I am afraid I find unsurprising. It remains a deeply conservative institution. But I had not previously encountered the argument that 90% would lose the money from universal credit anyway, and it is stunningly cynical. But on close consideration, I cannot work out what it means. Either there must be some additional cut to universal credit, or that those who lost tax credit could have regained it on universal credit anyway. If anybody could explain that one further, I should be grateful.