Campaigners trying to change the way a Devon constituency chooses its MP have been accused of trying to restrict democracy by the Conservative they are trying to unseat.

Anthony Mangnall’s Totnes seat is in the sights of a group trying to unite the non-Tory vote in a bid to get rid of him.

The group – South Devon Primary – believes that if Labour, Liberal Democrat, Green and other non-Conservative voters unite behind one opposition candidate, they can end almost a century of Conservative domination in the town.

The group’s campaign has been highlighted in a Guardian article by author and activist George Monbiot, who lives in Totnes.

He said the first-past-the-post UK electoral system is ‘unfair by design’, and in 229 out of 650 constituencies, votes against the successful candidates outweighed the votes in favour at the last general election.

Mr Monbiot said the Totnes constituency, which will be larger and will be called South Devon by the time the next election comes around, was an example of what campaigners called a ‘progressive tragedy’.

“The Tories have held this seat for almost 99 years, and the split progressive vote threatens to sustain their hegemony,” he said. “The problem we face here, as in many other constituencies, is that everyone opposed to the Conservatives has to guess other people’s intentions in seeking a tactical overthrow.”

The South Devon primary will consist of eight meetings in the space of a fortnight at different locations across the constituency. Non-Tory candidates will speak, and the audience will be asked which of them they believe is the best bet to oust Mr Mangnall.

A secret ballot will then be taken at the end of the meeting.

“This strategy offers more than just an end to minority rule,” wrote Mr Monbiot. “It also has the potential to undermine the power of dictatorial party leaders, of whatever persuasion, and return power to constituents.”

Another, similar, campaign is being mounted in the Godalming and Ash constituency in Surrey where chancellor Jeremy Hunt will stand in the next election.

South Devon Primary’s website says: “Conservative MPs have won in South Devon (Totnes) constituency for the last 100 years and often with a lot less than 50 per cent of the vote. Until we change our out-of-date voting system, we need a new approach.

‘The opposition is fragmented, giving this irresponsible government absolute power on a minority vote. Let’s rally behind a single progressive candidate whose values the majority of us share.”

But Mr Mangnall isn’t happy about the South Devon Primary campaign.

He said: “It is disappointing to see a group of people attempting to restrict democracy across South Devon by denying residents a wide field of candidates.

“While I applaud anyone for getting more involved in the democratic process, I think this campaign might be at odds with the wants and needs of South Devon residents.“In the meantime, I look forward to continuing my work delivering for South Devon and helping all those in need.”