The UK's decision to split from the EU is just a symptom of Britain's broken political system, according to Labour's Clive Lewis.

The former shadow business secretary, who quit Jeremy Corbyn's top team in protest over a three-line-whip being imposed on Labour MPs for the Article 50 vote, is one of the most vocal supporters of an anti-Conservative Progressive Alliance at the general election.

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Lewis, a former officer in the Territorial Army, is defying his party by backing the tactical voting pact.

But he told IBTimes UK that the first-past-the-post voting system was out of date and the Progressive Alliance, between the Liberal Democrats, the Greens and the Women's Equality Party, could help address the issue.

"When the Labour Party was formed and when it has been at its best it has been a progressive alliance," Lewis said.

"[William] Beveridge, who helped set up the Beveridge Report which helped create the welfare state, [John] Maynard Keynes, these are both liberals who worked with the Labour Party.

He added: "What we see now is that electorate has changed, it's no longer the same electorate it was in 1945. There are no longer four million manual workers, one million coal miners, the electorate has changed, it's dissipated. Many parties speak to different parts of the electorate.

"The Labour Party doesn't speak to them entirely. I think you can either say 'well, we are the way of the light and we can absorb all of them'.

"Or you can actually say 'we want a strong Labour Party, but we understand that we are perhaps the biggest tent but on the campsite of others'.

"What we have at the moment is an electoral system which is shoehorning a multi-party system into a two-party electoral system and that's wrong. We can see that politics is broken, Brexit was a symptom of that and people want to see a change."

Lewis, the MP candidate for Norwich South, is defending a majority of more than 7,600 votes from the 2015 general election. Unlike the rest of Norfolk, the East Anglian city backed Remain (56.2%) at the EU referendum. This factor may help Lewis secure victory on 8 June.

But with the Conservatives up to 20 points ahead of Labour in the opinion polls and heading for a landslide, the University of East Anglia's Dr Chris Hanretty has estimated that Lewis has just a 26% chance of holding on to the seat. The Tories, however, a 74% chance of taking Norfolk South from Labour.