Speculation that Downing Street plans to make up to 40 new life peers in July after the EU referendum, most of them Conservatives, should be taken seriously. David Cameron has the means (the prime ministerial patronage system), the motive (stopping the government defeats in the Lords), and the opportunity (he may not be prime minister by summer 2017) to do this. He also has past form on stuffing the Lords. All this makes the stories this week depressingly credible. The move should be stopped in its tracks by the body that has the power and responsibility to do so: the House of Commons.

The case against more peerages could start and end with the argument that it is morally wrong for the head of government to appoint the legislature. But there is more to object to. Mr Cameron has become a serial stuffer. He has sent 244 people to the Lords as prime minister and 56 since May 2015 alone. Another tranche will put him on course to be the most generous dispenser of peerages of our era, well above Tony Blair, who had the real excuse that in 1997 the Lords was heavily stacked against Labour. It is true that Mr Cameron has no majority in the Lords, even though the Tories are the largest single party, but this is partly because of the 178 cross-benchers who make any read-across between the Commons and the Lords tendentious.

There are, though, two more fundamental objections. The first is the disgrace that is the size of the House of Lords, currently 816 strong. Counting peers and MPs together, this means the UK parliament now contains 1,466 members. Merely to state this figure is to make an irresistible case for change. Yet the only change Mr Cameron’s government is contemplating is a reduction in the number of elected MPs from 650 to 600. This will further reduce representation from Scotland and northern England while the rich and successful (likely to be mainly from London and the south) are ushered into the upper house. It beggars belief that such a shift towards privilege can be taking place in the name of fairness in the 21st century. It is one that only parliament (or, in theory, the Queen, since she has to approve peerages) can do anything to change.

The second overriding objection is to an almost 18th-century prime ministerial patronage system that would not have disgraced Walpole. Mr Cameron’s last list of peerages was full of backers, beneficiaries and trusties. It also included a list of more minor honourees, including advisers, that was unprecedented in recent times. The next one is unlikely to be different. The alleged intention to reward financial and political backers of Mr Cameron’s EU campaign, perhaps even as an inducement to change sides, should be fingered, if it is true, for what it would be: political bribery.

Last summer, when Mr Cameron made 45 new peers, there was the beginning of a revolt against the patronage system. Then, in the autumn, the government lost a Lords vote on tax credits and the reform focus shifted to the Strathclyde review of the upper house’s powers over delegated legislation. Both houses now need to resume their focus on the bloated size of parliament and on patronage. Other parties and independent-minded Tories should follow the Scottish Nationalists, and condemn a system in which the government is at the same time seeking to reduce the number of elected parliamentarians and to increase the number of those who are appointed. The current system is a disgrace to the way this country does its politics and to the credibility of representative government. It cannot be allowed to continue in this way.