An 80-year-old who assumed he didn't qualify for the state pension has been handed a £140,000 payout after not claiming it for almost a decade.
The retiree, who wishes to remain anonymous, mistakenly thought he was not entitled to the state contribution because he had continued to work long after reaching retirement age.
However, the pensioner is now set to receive more than a decade's worth of payments in one lump sum.
The error only came to light after Wakefield Council made inquiries on the man's behalf.
In a report, councillor Michael Graham said: "To help our residents get more money in their pocket, we are using information we hold to identify if they are entitled to more benefits and allowances than they are getting.
"One particular resident, an elderly gentleman in his 80s, who was in credit with his council tax but wasn't claiming the correct benefits.
"The gentleman is still working and didn't want to stop but didn't realise he could claim his state retirement pension and continue to work.
"We contacted the pension service, who looked into it and told the gentleman that he was due a backdated lump sum of £140,000 as well as an extra £185 a week."
Have you discovered a huge windfall? Get in touch: emma.munbodh@mirror.co.uk.
Could I be owed money?
It's unclear as to how many more people may be missing out on their state pension, but experts say the 80-year-old is not alone.
Some may be under the misconception that they will automatically receive a pension when they retire, when the reality is that if you do not actively claim it, the money will automatically be deferred - as has been the case here.
This is because the state pension used to be split into two parts: the basic state pension and State Earnings Related Pension Scheme (Serps).
In some cases, workers made the decision to 'contract out' of Serps when they were employed, which meant they and their employer paid less National Insurance.
The downside meant that they'd receive a lower state pension - with the idea being that their employer would enrol them onto a company pension to make up the difference.
However, people weren't told that opting out of Serps would not affect their entitlement to a basic state pension.
I'm about to retire - how can I make sure I get a pension?
Around four months before you reach state pension age, you should receive a letter from the Pension Service informing you of how to claim.
If the Pension Service does not hear from you, it will automatically defer your payments.
Steve Webb, director of policy at insurer Royal London, said: "If you are over pension age and have not received anything, you should call the Pension Service.
"If it does not hear back, the Pension Service assumes that taxpayers want to defer their state pension. But the letter may not have reached its destination."
Under new rules, introduced in 2016, you need 35 years of National Insurance contributions to qualify for a full state pension - £168.60 a week.
Anyone with less than 10 years will not get a penny, but will be able to claim other benefits such as pensions credit instead.
A Department of Work and Pensions spokesman said: "We want everyone to be able to claim what they are entitled to and have a wide range of channels where people can get information and advice."
You can claim online at gov.uk/get-state-pension or find out more about the state pension, here.
According to Government figures, £20billion worth workplace pension savings is also currently unclaimed. Here's how to check if you have a lost pot.
