Everyone agrees that we are not building enough houses, and that the lack of supply is making homes unaffordable for many people.

But all the main parties are proposing different solutions.

Today David Cameron announced a new Conservative policy: a Tory government would aim to build 200,000 new homes over the next parliament for first-time homeowners to buy at a 20 per cent discount.

What’s in the small print?

Who’s got the worst record on housing?

Both Labour and the coalition like to highlight each other’s failure to oversee the construction of enough houses.

Ed Miliband has repeatedly accused Mr Cameron of presiding over the lowest level of homes built in peacetime since the 1920s. The exact same charge is levelled at Labour on the government’s website.

Both claims are substantially right and there isn’t much to choose between the parties.

Government figures say 137,450 dwellings were completed in 2010/11, which was the lowest since records began in 1969. But completions fell even lower to 135,510 under the coalition in 2012/13.

If you go by calendar year not financial year, show slightly fewer homes were built under Labour spending plans in 2010 (137,280) than in 2013 (137,980). The 2010 total is the lowest since World War Two.

What are the Conservatives going to do?

Mr Cameron is extending an existing policy on starter homes and doubling the target of homes to be built under the scheme from 100,000 to 200,000 over the course of the next parliament.

The plan is for developers to build homes more cheaply on brownfield land and sell them at 20 per cent below market value to first-time buyers under 40.

There will be rules to stop the buyers flipping their new home for an instant profit or letting it out.

The government will not directly subsidise the housebuilders. Instead, they will make a saving by being exempt from the usual Section 106 obligation to build a certain amount of affordable housing and contribute to local infrastructure costs.

So clearly, there will be an indirect cost to the state: we will get fewer affordable homes and councils may have to spend more on local services.

In 2013/14, 42,710 affordable homes were built in England – the lowest number since 2004/05.

A reduction in affordable homes built through Section 106 agreements with housebuilders could lead to even less affordable housing, although only about 15 per cent of all affordable homes were funded through this route last year.

The government says it will build 275,000 affordable homes over the next Parliament – more than in “any equivalent period in the last 20 years”.

What kind of houses will be built?

Mr Cameron said today: “We’ve shown what we expect starter homes to look like – not rabbit hutches or shoeboxes, but decent, well-built, homes with gardens – places to start and raise a family.”

This sounds like there will some kind of minimum standard in place governing the size of the new homes. But it appears this will be a case of government setting out guidelines rather than laying down rules.

In a statement today, housing and planning minister Brandon Lewis said: “A new design advisory panel set up by the government, involving leading industry experts, is developing an initial set of exemplar designs for starter homes which we expect to publish shortly for wider comment.

“While recognising the need for local flexibility, we would expect these designs over time to become the default approach to design to be considered for starter homes developments.”

What are the other parties proposing to do?

The Lib Dems say they to see 300,000 home built a year by 2020. For Labour it’s 200,000 a year by the same deadline. Ukip hasn’t set out an annual target but says it wants to build “a million homes on brownfield” by 2025.

The Greens, whose leader Natalie Bennett was widely criticised for muddling her figures in a radio interview last week, have arguably the most ambitious target: 500,000 new social rented homes alone by 2020.

Ms Bennett couldn’t produce the figures under pressure, but the Greens have set out costings for this policy.

The party says it will spend an addition £19.5bn on building new social housing by 2020, with the money coming from savings that will supposedly be achieved by cutting tax relief for private landlords.