Letter to the editor: Did you know there are almost 20 million Oyster cards in existence, often left in people’s drawers, which haven’t been used for more than a year?

In total there is £53m of credit left on these cards.

If you have an unwanted Oyster card, any money left on it can be claimed back and if you paid a deposit for the card, this is returnable as well.

At present the best way to claim your money back is by calling the Oyster contact centre on 0343 222 1234.

But within a few weeks it should be possible to claim a refund at any Tube station as well.

It is a shame the Mayor of London and Transport for London have kept quiet about this unused money for so long and made it a hassle to claim a refund.

CAROLINE PIDGEON, leader of the Liberal Democrat London Assembly Group