Londoners will not be surprised to learn that the issue of affordable housing in the capital has dominated the debate ahead of the Mayor of London elections in May. The average property price in the capital hit a staggering £537,000 ($751,773) in November 2015, according to the Office for National Statistics (ONS).

The official figures mean home owners in London have to folk out almost twice as much for a property compared to the rest of the UK (£288,000). Affordable housing is simply not a concern City Hall hopefuls can afford to ignore.

Unsurprisingly Sian Berry, 41, wants to avoid going anywhere near the Green Belt. The Green Party candidate instead wants to encourage development on unused land owned by Transport for London (TfL), among other things.

"We can get the 200,000 homes we need off largely the land we already have within London. It's a very long time before we need to be going anywhere near the green belt and the model I've got for that is to start off with Transport for London land – there's many, many acres of land," the Camden councillor told IBTimes UK.

"TfL have just signed off on 13 really big deals with big developers for that land. And there's a lot more to come. I want to break it up into smaller units, involving local communities.

"That way you get the homes more quickly and more affordably – we cannot rely on the big deals with the big developers, it just isn't working."

WATCH: Ukip candidate for Mayor of London speaks to IBTimes UK

The immigration issue

But what about another hot topic of discussion that has been linked to the affordable housing crisis? Immigration.

"You can't really just talk about supply without talking about demand. You have got to know how many people you are planning for and at the moment we have absolutely no way of doing that," Ukip's hopeful for City Hall told IBT in November.

But Berry blasted Peter Whittle for his "inhumane" comments. "Our immigration in London is people coming to work, people coming to join loved ones, people who are in relationships coming to move here − putting up barriers for those people to come is going to hurt London," she declared.

The Green hopeful stressed that London's technology sector, in particular, relied on the inflow of migrants to capital. "It's very, very backward-looking to wanting to put up a fence and say 'no more people for London,'" she added.

The latest data from the Office for National Statistics (ONS) showed net migration had hit 323,000 in the three months to September 2015. The figure was 31,000 more than over the same period last year, but 13,000 below June's record net migration high of 336,000.

Baroness Jenny Jones achieved a solid third place for the Greens in the 2012 Mayor of London elections. Berry hopes to do better, but the latest opinion poll from YouGov put Ukip's Whittle ahead of her on first preference votes.

The survey for LBC Radio, of more than 1,000 people between 18 and 21 November, put Berry on 5% and Whittle on 6%, with Labour's Sadiq Khan 10 points ahead of the Conservative's Zac Goldsmith in the second round (55% versus 45%).

Mayor of London candidates

  • Zac Goldsmith (Conservative)
  • Sadiq Kahn (Labour)
  • Sian Berry (Green)
  • Caroline Pidgeon (Liberal Democrat)
  • Peter Whittle (Ukip)
  • George Galloway (Respect)
  • Winston McKenzie (English Democrats)
  • Paul Golding (Britain First)
  • John Zylinski (Independent)
  • Rosalind Readhead (Independent)