Depending on the girth, lounging ability and wakefulness of the inmates, there are now roughly twice as many people entitled to sit in the House of Lords as there are spaces on the padded red benches for their ennobled posteriors. If all 826 turned up – but let's not be silly – the place would resemble a casualty clearing station.

These days, the Upper House qualifies as one of the least exclusive clubs in London. The United States Senate gets by with 100 people named Mitch, Chuck, Bernie and the like. Germany's Lander send 69 delegates to the Bundesrat. In France, membership of the Senate was increased to 348 a few years back to “reflect population growth”. Seanad Eireann copes with a mere 60 members.

Holyrood, meanwhile, is a unicameral parliament. Its committees are supposed to do most of the work of a second chamber. The claim is questioned, but hopes for a full-scale “revising body” in Edinburgh tend to fade when Westminster's peers are mentioned. The Lords gives upper houses a bad name.

The reasons are well-rehearsed. In fact, they have been rehearsed to death. David Cameron's abuse of his patronage powers to reward chums, underlings, donors and favourites is part of a tradition far older than the 96-year-old Lord Carrington, the former Tory minister who has been adorning the Lords since 1945. Mr Cameron's enthusiasm for non-elected legislators might be spectacular – an average of 44 a year, thus far – but there is nothing novel about it.

“Reform” of the Lords has been a Westminster hobby since the 1911 Parliament Act. Aside from the disappearance of all but 92 hereditary peers in 1999, precious little has changed since then. Proposals come and go, government by government, but only tinkering follows. Once there were more than 800 individuals entitled to sit in the Lords because they had inherited titles. Now there are 826 peers, most drawn from a self-preserving political aristocracy. Spot the difference.

A cynic might suspect that those with the power to enforce change have no real interest in change. There is the possibility – shocking, I know – that they regard an unelected legislature founded on naked patronage as a convenience rather than an embarrassment. What's plain is that they talk endlessly about reform until the moment their turn comes around.

Take the poor, beleaguered Liberal Democrats. They have maintained for years, for generations, that they would scrap the unelected Lords if only they were given half a chance. So do they boycott the institution? Not quite. Destroyed in May, the party has just eight MPs these days, but an army of 112 peers. For the panjandrums of LibDemmery, accepting 11 new peerages to Labour's eight, political defeat has become merely theoretical.

And what of the People's Party? Coasting towards catastrophe in the spring, Ed Miliband had plenty to say about replacing the Lords with an elected senate to represent the “regions and nations”. He forgot that he had helped the Tories to foil LibDem hopes of reform when the Coalition still functioned. Mr Miliband was determined, he said, to give every part of Britain “a voice at the heart of our politics”.

If nothing less would do, surely Labour would have nothing more to do with an unelected Lords beset by corruption scandals? Just a couple of days ago, indeed, Roy Hattersley announced at the Edinburgh Book Festival that he is quitting a “vastly inferior institution” that “goes against the idea of equality”. True, it took him 18 years to achieve this insight, but the party's former deputy leader has a point. Why would Labour damn the Upper House yet keep it alive?

Perhaps, if you're Alistair Darling, it's just another noble way to save the Union. The former Chancellor did agree last September that a bloated Lords needed “looking at”, but he did not say how closely he would look. Similarly, when Peter Hain last November dismissed the Lords as “an archaic anomaly which fuels disillusionment with British politics” he did not specifically promise that he would never become Lord Hain of Neath. All in the cause of reform, of course.

This sort of thing barely qualifies as a joke. When the bulk of the hereditaries were dispensed with, the excuses for Westminster's failure to join the modern world disappeared. The old claim that an elected Upper House would compete with the Commons for authority was always risible: its powers could be restricted much as the powers of the Lords are restricted now. The argument that elections would grant too much power to parties was meanwhile exposed as a nonsense, yet again, by Mr Cameron's behaviour this week.

You could wonder, in any case, why 92 individuals with inherited rights are still involved with legislation in the 21st century. You could ask the same, if only for fun, of 26 “Lords Spiritual” – “bishops”, as English folk know them – or of the gender imbalance that allows three male peers for every woman able to face life in the Upper House. The point of abolishing the Lords is to eradicate this sort of offensive rubbish, but also to replace Lord Hattersley's “inferior institution” with something fit for a democracy.

Let's not be naive, however. All governments treat the Lords as a convenient source of ministers who need not bother with election or, come to that, scrutiny from MPs. Gordon Brown's administration certainly acquired the habit of ennobling individuals just to give them ministerial jobs. We can pray that Mr Cameron has no such plans for the unproven political talents of Michelle Mone, the lingerie pioneer, but you never know. Her peerage and appointment to aid young entrepreneurs from deprived backgrounds blurs several lines.

The Lords is not irrelevant. Mr Cameron is packing the Upper House precisely because the numbers are not to his advantage. Without reliably reactionary aristocrats to hand, the Tories feel a little exposed. With a slim enough Commons majority, they could do without repeated defeats from opposition and cross-bench working peers.

They do work, some of them, for their parties of choice. There are plenty of tales of peers living well thanks to a tax-free £300 daily allowance and expenses. There are plenty of jokes about an institution in which the average age is 70, 29 members are nonagenarians, 136 in their 80s, and just a handful under 50. For many, Lord Sewel's recent resignation added to the comedy. But the Lords is central still to the legislative process.

It just happens to be stuffed (in every sense) with people who needn't worry what voters think. One part of the decadence of Westminster is that few who inhabit the place find this remarkable. They place the making of laws beyond scrutiny or challenge while claiming status and ermine in the British caste system. They maintain a system of patronage that is profoundly corrupt and tell the rest of us that theirs is merely a reward for “public service”.

If they were serious about reform, and serious about a properly federal Britain, an interesting test would arise. Just how many of the 826 taking upwards of £20 million annually from the public purse could win at the polls?