For over two years, Sean Mulryan’s property giant Ballymore has been working alongside British grocery chain Sainsbury’s to win over Londoners and planners to build a new neighbourhood in the west of the city. On Tuesday, it finally secured a crucial approval from a London borough to push ahead with its development. The Royal Borough of Kensington and Chelsea (RBKC) has voted in favour of supporting the project. The Irish developer and Sainsbury’s massive £3 billion (€3.4 billion) mixed-use development that includes the construction of over 2,500 new homes and the development of a flagship store for the supermarket giant, as…