The Mayor’s intention is for developers to give a legally binding commitment that they will provide affordable space for independent retailers in any new major development.
Johnson’s support for the sector has been welcomed by the Association of Convenience Stores (ACS), but it warned that his plans could backfire if not properly implemented.
ACS chief executive James Lowman said: “This is an idea that has gained currency in recent times, but we do not see it as a credible safeguard for diversity.
“This type of scheme is often a soft concession by developers, targeted not at increasing competition, but allowing the co-existence of non-competitor specialist boutiques in massive developments.
“In this situation a poorly planned or unnecessary development will still harm diversity in a whole local market.”
Johnson caused controversy last month when he wrote in the Daily Telegraph that he would shop at a new Tesco store near his home in Islington, despite having concerns about the power of the multiple giant.
“With a guilty ‘ching ching’ I will add to Tesco’s profits, because hypocrisy is at the heart of our national character,” he said. “The British are at their most hypocritical when it comes to supermarkets.”