Transport for London (TfL) has rolled out contactless payments across the UK capital's transport network, making it more convenient for anyone that wants to pay with a card and considerably less convenient for thousands of commuters.
The arrival of contactless payments allows those with credit and debit cards with NFC / PayWave to get through the ticket gates on London Underground, trams, DLR and some overground services.
It will cap payments over a week, but not over longer periods and is likely to court huge controversy because of 'card clash'.
Clash of the tight ones
The current Oyster system uses an NFC card for entry and thousands of commuters have monthly or annual travelcards. If they keep that card in the same place as a credit or debit card then they could find that they are debited from their card rather than using their pass.
Another major issue could be that the two cards in close contact can cause the NFC to fail.
Of course, TfL have been at pains to point out that this is not their problem but their customers' and that they should not keep their cards together.
Shashi Verma, TfL's Director of Customer Experience, said: "Accepting contactless payments on transport in London is a fantastic achievement for our city – it provides our customers with the most convenient way to pay for their travel and highlights the capital's position as a world leader in transport ticketing, technology and customer service.
"Oyster will continue to be available, with contactless payments being another option that lets our customers travel without the need to top up Oyster credit.
"I would like to remind all of our customers to only touch one card on the reader to avoid paying with a card they did not intend to pay with."
We're at the launch of the new system, and will be asking about these potential problems.