Reforming the House of Lords is set to dominate the coming session of Parliament. It remains a totemic political demand of the Lib Dems and the Government has agreed to fast-track reform into law by including in the Queen's Speech, the Coalition agreement to elect by PR at least 80 per cent of the Lords.

If rumours are to be believed, the joint committee charged with realising this goal is to recommend an Upper House of 450 peers, 80 per cent elected and 20 per cent appointed, with a 15 year non-renewable term. The biggest shock has been the committee's recommendation for a referendum on any constitutional change, a move the Lib Dems, fearing a repeat of the AV fiasco, bitterly oppose.

The real shame is that the committee is ducking the issue by endorsing some very bad ideas for reform while passing the buck to the electorate in the hope they will vote the whole matter down. By failing to produce a viable alternative to the Coalition's proposals, the committee is eschewing its constitutional responsibilities, leaving us with a choice between the indefensible and the unconstitutional.

For it is not clear that an elected House of Lords is a good, progressive or even constitutionally literate proposal. The proposed electoral system will simply extend the dominance and control of the main political parties and increase the writ and power of the executive. Moreover, the joint committee has bizarrely recommended an open preferential voting system which in Australia has resulted in parties controlling the lists, further strengthening their grip.

If the reform proposals succeeded we would see a decline in the diversity of opinion expressed and a House less representative of the population than it is currently. Representative democracy in a modern society simply lacks the means to deliver anything but party dominance. Independence of mind and distance from party dictate is exactly what people find most democratic and valuable in the Lords. Paradoxically, wholesale election puts this at risk.

Plus, an elected House of Lords would quickly destroy the complementary relationship that exists between the two Houses of Parliament, providing the Upper House with a competing democratic mandate. We would then replicate the worst of the American political system through partisan conflict between the Houses.

Most worryingly, the proposed reforms are profoundly unconstitutional – they fail to recognise our own tradition and act as if our mixed constitution has no enduring merit. Britain survived the revolutions of the past two centuries that ruined virtually every other European nation. And this is due in no small part to our mixed constitution which secured the practice of democracy by uniting it with the principle of plurality and ensuring that the democratic process was never wholly captured by one party, elite or faction. The endemic flaw of purely democratic polities is that they cannot secure a general national good beyond the narrow interests of sectional politics or naked self-interest.

British principles of an organic and mixed polity should ensure that our democracy is inextricably allied with the principles of plurality and participation. In that respect the reforms proposed are a constitutional dereliction. Yet, the status quo is equally unsustainable. We need to think again and – in line with our constitutional principles – recast the Lords as a hybrid composed a third each of appointed, elected and nominated members.

The third of Lords selected by appointment should be from civil society.Representatives could be selected by an appointments panel whose express brief would be to populate the Lords with distinguished figures from an array of professions, including universities, trade unions, charities, the armed forces, the police, business, sports, the arts, the sciences and all the major faiths. Our politics needs those who are esteemed in their professions and not subject to any political whip or partisan concord. These are the crossbenchers of tomorrow.

To be truly representative of society, the Lords must incorporate election but have some element of regional representation. The surest way to engage a public exhausted by traditional politics and revive their faith in elected representatives, is to provide them with independent advocates for their towns or cities whom they can truly regard as their own. Election is the obvious means of selecting suitable regional representatives but a form of non-partisan election which bans party-based nomination would do much to enrich our electoral politics.

The House is political and so, a degree of party involvement is essential. The final third of the Lords should comprise members nominated by the parties, perhaps on the basis of their share of the Commons vote.

So yes, let's reform but let's note that an elected house would be the greatest extension of government and executive power we have seen since Charles I dissolved Parliament in the 17th century. For democracy's sake we must oppose an elected House of Lords.

Phillip Blond is director of ResPublica. The think tank's essay collection on Lords' reform, 'Our House', is at respublica.org.uk