Nearly 80% of over 50s believe they have been rejected for a job because of their age, while a further 33% think that age prejudice starts at around 45.

These are the results a survey carried out by the charity Age Concern London and employment agency Reed Consulting, which polled 3,000 people over the age of 50.

Further results revealed that 48% of the respondents wanted to work past the state retirement age. However, the charity estimates that currently more than 250,000 over 50s are unemployed but would like to work.

A spokesperson for the charity said: “This represents the largest pool of under-utilised skills and experience available to the London economy and is equivalent to a full 7 per cent of the capital’s workforce.”

The charity is urging employers to reassess their attitude to older workers in the face of demographic change: there will be three non-workers for every worker by 2031, compared with a ratio of 1.1 currently.