From Thursday, Londoners will be able to pay for some bus journeys using their contactless bank cards.
Transport for London (TfL) confirmed last February plans to upgrade all Oyster card readers across the capital to work at the touch of a bank-issued debit or credit card.
It had hoped to have the new system up and running on all of London's 8000 buses in time for the Olympic Games, with the Tube, DLR, Tram and London Overground network following by the end of the year.
By May the timeline was scrapped though, with Shashi Verma, director, customer experience, TfL promising: "We will only roll it out once we are confident it is 100% robust."
The switch to contactless bank card payments is designed to reduce commissions and processing costs for TfL, as well as making life easier for commuters who will no longer need to have - and top up - a separate Oyster.
However, the move has faced criticism, with a report last November from the London Assembly branding it "unconvincing", raising questions about the fairness, security and cost-saving potential of a new system.