Mayor Boris Johnson says 174,000 men and women are missing out on an extra 35-pounds a week.
So as part of his "Know Your Rights" campaign, he's urging the capital's older residents - and their carers - to check they're getting all the payments they're entitled to.
The details now from Liz Wickham.
More top news
A luxury penthouse in Mayfair has just broken the record for the most expensive home ever sold in the UK
Simon Harris talks to the Labour politicians hotly tipped for the Mayoral race in 2016 - but only one will admit he is standing
ITV London's Political Correspondent Simon Harris takes a look at the Labour candidates vying for the capital's top job in 2016