Political parties and MPs have forged a new cross-party consensus on replacing the UK’s First Past the Post voting system with a form of Proportional Representation.

First of its kind in British politics and brokered by campaign group Make Votes Matter, the “Good Systems Agreement” sets out the principles that a new voting system should deliver and calls for a citizens’ assembly to recommend one for the UK.

The signatories want a proportional voting system in which “seats closely match votes” and all votes count equally, wherever in the UK they are cast. The agreement calls for a system which maintains the geographical link between MPs and constituencies and allows the public to vote “for people rather than just parties”.

The precise system should be “determined by citizens through an evidence-based, deliberative process”, such as the ‘citizens’ assembly’ that broke the deadlock about reproductive rights in Ireland, the document says.

Signatory parties in the “Make Votes Matter Alliance” – including the Brexit Party, Green Party, Liberal Democrats, the Alliance Party of Northern Ireland, Plaid Cymru and the SNP – received more than two-thirds of the votes cast in May’s European elections and are joined by a number of Labour, Conservative and Independent MPs.

Jonathan Reynolds, Labour MP for Stalybridge and Hyde, said: “This new cross-party agreement urges everyone in politics to get behind a voting system that ensures seats match votes, while making clear the need to retain the local constituency link between MPs and voters. I’m pleased to add my name to it.”

Richard Tice MEP, Chairman of the Brexit Party, said: “Parliament’s handling of Brexit has been an abysmal failure. The political establishment has shown time and again that it cannot be relied upon to represent the people, but these failings are entrenched by First Past the Post. We need to bring in Proportional Representation to change politics for good – and this agreement will help bring that about.”

Vince Cable MP, Leader of the Liberal Democrats, said: “First past the post leaves millions of people feeling powerless and excluded; robbed of their rightful say over how our country is run. Government is much more likely to act for the common good when politicians and parties are responsive to all the people, not just a few swing-voters in a handful of marginal seats. Liberal Democrats have always campaigned for fairer and more democratic elections. I’m delighted members of other parties are working with us in the Make Votes Matter alliance to set out the principles that should shape a new proportional system for the House of Commons.”

Derek Thomas, Conservative MP for St Ives, said: “The First Past the Post voting system we use for general elections means that many voters do not feel they have a stake in our democracy. Electoral reform alone will not return trust to politics, but I believe we have little chance of truly rebuilding trust without it. This is why I have joined a new cross-party agreement about the kind of democratic system we need – and how we should get it.”

Jonathan Bartley, co-leader of the Green Party, said: “We know that fair, proportional electoral systems produce better decisions and policies, with people working together to contribute to the best way forward. This makes the Good Systems Agreement an elegant way forward, as well as an essential one. It is bringing a modern, consultative, cross-party approach to designing the kind of system that will make democratic, sensible decision making the normal form of politics.”

Liz Saville Roberts MP, Westminster Leader of Plaid Cymru, said “Parliament is supposed to represent the whole electorate, but there are many who will not feel represented until seats match votes. Votes should count equally, wherever they are cast and whoever they are cast for. We need a citizen-led process to recommend a new voting system for our general elections.

Klina Jordan, co-founder of Make Votes Matter, said: “There is now greater consensus than ever about the need for a proportional voting system, the features that system should have, and the route to getting it. The current system is failing on its own terms so badly that the next general election will likely produce another government without a clear majority. When that election comes around, this agreement will be at the forefront of any negotiations that follow.”

The UK is the only country in Europe – and one of only three major democratic developed countries – to use First Past the Post for general elections. Campaigners claim the system means Parliament does not reflect the votes cast, shutting millions out of politics, and forcing many more to vote tactically. First Past the Post no longer delivers its supposed main benefit of “strong and stable” majority government, they add.

The agreement will be launched at an event in Parliament today (Tuesday 2nd July) hosted by Tommy Sheppard MP (SNP), featuring speakers from the signatory parties.