As the Coalition Government has reached its mid-point Compass have signed a joint letter urging progressives to ensure that a renewal of a Conservative/Liberal Democrat arrangement does not become the default option in the event of another hung parliament. The edited version is written below.

• An extended version of the letter is available to read and comment on the Shifting Grounds website here.
• A write up of the intervention is featured on Guardian's Politics Live Blog (2.24PM)
• Labour Uncut are hosting a debate on the subject at http://labour-uncut.co.uk/

With David Cameron and Nick Clegg setting out the coalition's priorities up to the next election (Comment, 9 January), progressives must ensure that a renewal of that arrangement does not become the default option in the event of another hung parliament. All political parties will rightly campaign hard to win a majority and govern on their own, but the sensible ones will prepare for the possibility that voters deny them their wish. In those circumstances it is our belief that a Labour-Liberal Democrat coalition has the potential to give Britain a successful reforming government based on strong foundations of shared history and values.

An economic policy that combined deficit reduction with fairer taxes and an active industrial policy to stimulate growth would be the obvious starting point. The overlap between British Liberalism's longstanding interest in economic democracy and Ed Miliband's call for a responsible capitalism holds out the prospect of far-reaching reform. A Lib-Lab coalition really could become the "greenest government ever". There would be no more efforts to roll back rights and equalities legislation or divide society by demonising people in poverty. Creating an elected second chamber to replace the Lords would become a joint priority. Britain's policy on Europe would be based on engagement and reform, not hostility and the drift towards isolation. Turning that option into a realistic possibility will require a conscious effort to build new relationships and ideas. That is not something that can wait until after the next election. Both parties must begin that task today.

David Clark, Editor, Shifting Grounds
Linda Jack, Chair, Liberal Left
Richard Grayson, Vice-chair, Liberal Left
Ruth Lister, Chair, Compass management committee
Andrew Harrop, General secretary, Fabian Society
Roger Liddle, Chair, Policy Network
Patrick Diamond, Senior research fellow, Policy Network
Olaf Cramme, Director, Policy Network
Neal Lawson, Chair, Compass