In 2011, rental properties at 80% of market rent were added to the definition of affordable homes. Additionally, the government further expanded the definition this year to include starter homes, although regulations outlining the implementation of starter homes has not yet been issued.

According to the Financial Times, deputy mayor James Murray said: “We are intending to set out more clearly what sort of homes we consider to be affordable, which could include a range of products including, but not limited to, homes for social rent, shared ownership and London living rent”.

“We are unmoving working on the details… but it will be based on average household earnings. If you spend around a third of your earnings on rent and housing costs, that is generally considered to be affordable,” said Murray.

Khan will also be issuing guidance on a fixed affordable housing tariff. This fixed affordable housing level is currently expected to be 35% but this will be confirmed in the autumn. It will grant developers to opt out of the viability process and deliver a set level of affordable homes which should hurry up the planning process.

According to Estates Gazette, Murray said “We would crave to do it in a way that there is an incentive for applicants in the planning process to depart for that fixed contribution, rather than down the viability route, because it is supposed to be a quicker way of getting planning permission.”

Earlier this year, Murray also confirmed that supplementary planning guidance for viability will be published this year to offer a more “consistent and thorough” approach.

Planning expert Victoria Lindsay of Pinsent Masons, the law firm behind Out-Law.com, said: “Throughout Khan’s campaign to become London mayor he promised to set a target of 50% affordable housing across London, in stark contrast to his predecessor, Khan argued, who achieved a much lower rate. However, since Khan has been in office we own seen this strategic lengthy-term target of 50% reduce to an immediate target of 35% and several decisions already own been let through with a lower level of affordable housing secured”.

“Since the former primer minister David Cameron introduced the concept of starter homes to the political agenda while his government, there has been market uncertainty as to how this would fit with the affordable housing product as we discern it as it would push the top finish of the affordability spectrum. Therefore, clarification on the definition of ‘affordable housing’ and supplementary planning guidance on affordable housing and viability is to be welcomed,” Lindsay said.