THIS week marks the launch of a new cross-party consensus on reforming Westminster, of which the SNP is a founding signatory. The Good Systems Agreement, brokered by campaign group Make Votes Matter, sees parties and politicians from across the political divide coming together on the single issue of electoral reform.

For me, democracy is defined by two things. Firstly, the elected parliament ought to, in the broadest possible terms, represent the people who vote in General Elections. Secondly, the country should be governed with the consent of a majority of its citizens. The current first-past-the-post system fails palpably on both counts.

Our system simply does not produce parliaments that reflect how the people voted. In the 2015 General Election, three parties shared a quarter of all votes cast between them. Yet they ended up sharing just 1.5% of seats in the House of Commons.

And almost without exception, our governments go into office without the consent of a majority of voters. The Conservatives and DUP currently share a majority of seats, despite receiving just 43% of votes in 2017. In the past, parties have won outright majorities on as little as 35% of the vote.

READ MORE: SNP sign cross-party Make Votes Matter pact to change voting system

I believe parliaments that do not reflect the people and governments that rule without the consent of most voters have no place in a genuine democracy. I say that as a representative of the party that has probably been the greatest beneficiary of first-past-the-post in recent years. In 2015, the SNP took 95% of the seats in Scotland with 50% of the vote. My only defence is that we did not make the rules.

So we have joined with other parties from across the political spectrum in stating our shared ambition to change those rules. In this historically broad consensus, we join not only the Green Party, Liberal Democrats and Plaid Cymru, but MPs from Labour and the Conservatives – and even the Brexit Party. In the agreement, we set out the principles that we all believe must underlie a new voting system for UK General Elections.

Most important is the principle that seats should match votes. Everyone should also have a vote that counts equally, without regard for whether they are cast in the safe or marginal seats under the current system. We also share the belief that local representatives must be retained and that people should be able to vote for named candidates rather than just parties. We agree that, fundamentally, the public is best served by a parliament that reflects how they vote.

The National:

The Scottish Parliament already uses a voting system that strives to deliver these principles, as do the UK’s devolved assemblies and many parliaments overseas. But importantly, the agreement does not choose a particular system. Instead we call for a citizen-led process – such as a Citizens’ Assembly – to choose the best voting system for the UK.

I always find it strange that nobody seems to disagree with the principle that seats in parliament should reflect the votes cast. Those who oppose change tend to say that it is a noble idea, but that for various practical reasons it will never work and so we should not bother trying.

READ MORE: Henry McLeish: Ditch first-past-the-post MSPs at Holyrood

But as more and more people see that this is not the natural order of things, and that people elsewhere in the world are better represented, it begins to fuel great disillusionment with our entire political process. Sometimes this results in people being apathetic and not turning out to vote. Even more worrying is the building resentment that many feel about a system that denies their democratic expression. That is why this change is so urgent.

Of course, I want Scotland to become an independent country so that we work together with other countries in Britain and Europe on our own terms. But, for as long as we are part of the United Kingdom, we will defend the democratic principle of a parliament that reflects the people. I believe both Scotland’s and the UK’s interests will be better served by a House of Commons that is representative of the voters and capable of compromise – perhaps occasionally even of consensus.

With one or two honourable exceptions, few in the UK’s current governing party believe in reform. With politics more unpredictable than ever, a change of government may not be far around the corner. It falls to the opposition parties – all of them – to have this discussion now about what a modern electoral system should look like. Some of the Labour Party’s representatives have led the way by adding their names to this agreement. I urge the Labour Party in its entirety to join the other minority parties in the House of Commons in advocating the principles that this new consensus is founded on. We owe it to every voter to put them back into the heart of our democracy.