More than 100 years ago the well-known radical socialist Winston Churchill said that it was “a serious national evil” that anyone “should receive less than a living wage for their utmost exertions”. Today both David Cameron and Ed Miliband claim to be united in calling for that evil to be eradicated from national life: in 2010 Cameron said it was “an idea whose time has come”. And in 2012 Miliband called it “a really important idea”.

Yet scratch below the rhetoric and you’ll see that the simple idea of ensuring that wages pay people enough to live on is a long way from being realised. In fact, under Cameron’s watch the problem has got worse – the number of people earning less than a living wage has risen by 50 per cent - from 3.4m in 2011 to 5.2m today. The government promised to make work pay; in fact it’s making work pay much less.

The Conservative and Labour approach of small carrots and no sticks – ranging from gentle encouragement to employers to pay their workers more to tax breaks to companies that “do the right thing” – isn’t working. For the first time since records began, the majority of people in poverty are in working families. Two-thirds of adults in these families are in work. Far too many workers – social care being a notable area of great exploitation – aren’t even being paid the legal minimum wage.

Fear and economic insecurity dog the lives of millions of households. They have little hope for improvement in their circumstances, little confidence that they’ll be able to pay the bills, and worry about going under, disappearing into the hungry jaws of payday loans and credit card bills.

What they need is hope; confidence that their lives will get better, less stressed, less fearful.

That’s why the Green Party is pursuing a different approach. Instead of asking nicely, we will make it a legal requirement for all employers to pay their workforce enough for them to live on: we will set a new target for the minimum wage to reach £10 an hour for everyone by 2020. We’d also immediately increase the minimum wage to living wage levels.

Of those 5.2m low paid workers nearly half a million are in the public sector. The cost of paying them all a living wage works out at around £360m – about 0.25 per cent of public spending. Ensuring all of Tesco’s 310,000 employees have enough to put food on the table and pay the bills would cost a fraction of the £2.4bn profit they are forecast to make this year.

Here in the UK we have one of the worst records on low pay in the developed world. We are twice as bad as the best performers: Belgium, Italy, Norway and Finland all have low pay rates less than half of ours. Only the United States has a worse record.

So anyone who is serious about building a fairer society and an economy that works for everyone, not just those at the top, really does have to have a credible plan to tackle poverty pay. The public expect it too – nearly eight in ten agree that “people working full-time should be paid enough to maintain a basic but socially acceptable lifestyle”.

Our £10 an hour policy is a part of a package of measures that will be included in our fully costed 2015 manifesto which will also set out our plans for a wealth tax on the top 1 per cent and pay ratios to ensure that the CEO isn’t paid more than 10 times the salary of the office cleaner.

More than a century after Churchill called for it, the Green Party will ensure that the living wage really is an idea whose time has come.

Natalie Bennett is leader of the Green party