The investigation by this newspaper into what the Deputy Prime Minister, Nick Clegg, has called the "murky world" of the House of Lords – and our reports on the practices of a number of its members – has highlighted the urgency of the case for reform of the second chamber of the British Parliament.

It is disturbing enough that one member of the Lords, the treasurer of the Conservative Party and hedge-fund wizard Lord Fink, may have broken parliamentary anti-sleaze rules by arranging to host a private promotional dinner in the Lords for a commercial company.

But this is not an isolated case. Other senior peers, including a former police chief, have used their position to arrange events for private companies in which they have a financial interest. Buying access to Parliament in such a way cheapens democracy and threatens to turn the second chamber into a House of Lobbyists packed with unelected, political appointees who can claim £300 a day just for turning up.

Meanwhile, the revelation that some of the Lords Spiritual claim maximum allowances, while others make no claim on the public purse, only underscores the difficulties inherent in the amateur status of membership of Britain's revising chamber. Those who make our laws should be elected and subject to the scrutiny that goes with that. It is an affront to democracy, and to the common sense of the electorate, that 21st-century Britain still has some 700 lawmakers appointed by ministers – a system which only entrenches patronage and cronyism – and another 92 who sit in the chamber on the basis of birth alone. Such a situation is an anachronism as indefensible as it is inequitable.

Reformers have been raising objections to the House of Lords for more than 100 years, to no avail. It is time for change. There is also an unusual political opportunity at hand. At the last election all three major parties included House of Lords reform proposals in their manifestos. Next week, the Cabinet will agree on the details of plans that the Coalition will put to the House of Commons, including a slimmed-down upper chamber with 80 per cent of its members elected, the rest appointed, and all sitting for a limited term. It is far from the most radical option. But it is a sensible and realistic proposal that deserves support.

Yet the signs are that the Government is getting cold feet. Reform was promised in the Queen's Speech, but only in vague terms and at low priority. Even Mr Clegg appears to have lowered his rhetorical sights, talking of introducing "a smidgen of democracy" into the House of Lords. And large numbers of Tory backbenchers insist the electorate will have no patience with Lords reform when politicians should be prioritising the economy. The argument is a bogus one. There is no reason for constitutional reform to monopolise parliamentary time, if politicians from all three parties deliver on their manifesto promises. But with the Government starting to feel the strain of coalition, political consensus is more difficult than ever.

Success is not impossible. If Conservative backbenchers can support elections for police commissioners, they should have no problem supporting elections for all politicians. Equally, Labour MPs must act with integrity, and stick with their party's stated position rather than seek temporary advantage in tactically opposing the Government. And Liberal Democrats might want to remind Ed Miliband that he may yet need their support, in the event of another hung parliament in 2015.

Mr Clegg has a once-in-a-generation chance to bring to an end a situation that makes a mockery of Britain's claims to democracy. It must not be wasted.