The contest will mark Berry’s third attempt at the mayoralty having stood in both 2008 and 2016, when she also successfully stood as a London Assembly member.
The reversible vests combine the standard orange high visibility version with a red version featuring a ‘Here to Help’ message on the back and have been introduced after London TravelWatch called for improvements to customer service.
The capital is the biggest beneficiary of a Department for London scheme which will fund a total of 263 new ultra low emission buses across England and Wales.
Some London Assembly Members and other interested parties have starting questioning whether increased pushback by the Board has led to changes in the way information is presented by TfL managers.
The organisation is highly dependent on public grants to remain viable, with its largest source of income being City Hall and the Mayor, but has historically refused to publish details of how it spends the cash.