An investigation by the Parliamentary and Health Service Ombudsman (PHSO) found that thousands of women may have been adversely impacted by the government's failure to adequately inform them of the change.

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To date, the Department for Work and Pensions (DWP) has not acknowledged its failings or put things right for those women, the watchdog said.

The ombudsman noted that the department has indicated it will not comply with the findings and called on parliament to intervene.

PHSO chief executive Rebecca Hilsenrath, said: "The UK's national ombudsman has made a finding of failings by DWP in this case and has ruled that the women affected are owed compensation.

"DWP has clearly indicated that it will refuse to comply. This is unacceptable. The department must do the right thing and it must be held to account for failure to do so. "

Ms Hilsenrath said that given the ombudsman's "significant concerns" the DWP will not act on its findings, "we have proactively asked parliament to intervene and hold the department to account".

She said: "Parliament now needs to act swiftly, and make sure a compensation scheme is established. We think this will provide women with the quickest route to remedy."  

The prime minister's official spokesman said the government would now "consider the ombudsman's report and respond to their recommendations formally in due course".

A DWP spokesman echoed the response, adding: "The government has always been committed to supporting all pensioners in a sustainable way that gives them a dignified retirement whilst also being fair to them and taxpayers.

"The state pension is the foundation of income in retirement and will remain so as we deliver a further 8.5% rise in April which will increase the state pension for 12 million pensioners by £900."

The findings follow a long-running campaign by the Women Against State Pension Inequality - often known as Waspi women.

The group say millions suffered financially as they were not given sufficient warning to prepare for the change to their retirement age.

The ombudsman's report suggested that, in the sample cases it has seen, women should receive compensation of between £1,000 and £2,950 - Level 4 on the compensation scale.

However, the findings are not legally binding.

Waspi women 'very disappointed' in DWP

Angela Madden, chair of Waspi, told Sky News she wanted to see the government grant Level 6 compensation of £10,000 or more.

While this would cost the exchequer around £36bn, she said the government "have saved £181bn by increasing the state pension age" for women.

"Had they told us, when they first decided in 1995 this was going to happen, we would have had 15 years notice," she said.

"I got a letter in March 2012, two years before I expected to retire, and that letter told me I wasn't getting my state pension until March 2020. I was absolutely devastated.

"I'd already given up work to spend time with my then ailing mother. I couldn't unmake that decision and had [I] had the right information. I wouldn't have made that decision."

She added that she is "very disappointed in the DWP" and called on whoever wins the next election to act swiftly on compensation.

"It needs to happen soon as more than 270,000 women have died since we started this campaign", she said.

Why was the state pension age changed for women?

The state pension age was aligned to match men in a move praised for improving gender equality.

For decades, men had retired at 65 while women had retired at 60.

A law was passed in 1995 setting out a timetable to eventually raise the retirement age for women so it would match the age for men.

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The original plan was to phase in the change over a 10-year period between 2010 and 2020 to allow people sufficient time to plan ahead.

However, in 2011 the coalition government accelerated the shift to reduce costs, with the increase in retirement age brought forward to 2018.

Waspi agrees with the equalisation of ages, but says they were not properly informed of the changes, giving them insufficient time to prepare or make other financial arrangements.

The ombudsman investigated complaints that, since 1995, the DWP has failed to provide accurate, adequate and timely information about areas of state pension reform.

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It published stage one of its investigation in July 2021, which found failings in the way the department communicated changes to women's state pension age.

The DWP's handling of the pension age changes meant some women lost opportunities to make informed decisions about their finances and diminished their sense of personal autonomy and financial control, the ombudsman said.

Liberal Democrat Chief Whip Wendy Chamberlain said Waspi women have "tirelessly campaigned for justice after being left out of pocket".

She added: "Liberal Democrats have long supported Waspi in their campaign and it is now up to this Conservative government to come forward with a plan to get these women the compensation they are owed."