Freedom Pass

Freedom Pass is a concessionary travel scheme, which began in 1973, to provide free travel to residents of Greater London, England who were aged 60 and over (eligibility age increasing by phases to 66 by 2020) or who have a disability. The scheme is funded by local authorities and coordinated by London Councils. Originally the pass was a paper ticket, but since 2004 it has been encoded on to a contactless smartcard compatible with Oyster card readers.

More information on the Wikipedia page.