Public sector pensions may lose 15 per cent But speaking about what this meant for workers, she said: "To get the same level of pension you will have to save more. That will be one of the consequences of this. RPI inflation is often higher than CPI because of the formula used to calculate it, with RPI inflation including some housing costs. Laith Khalaf, pension investment manager at Hargreaves Lansdown, said that according to some estimates, the change to CPI was the equivalent of a 15% average cut in the value of a pension. He said: "It's a fairly hefty blow that's been dealt." Brian Strutton, GMB national secretary for public services, said: "When the Government announced out of the blue in 2010 that it was downgrading the annual uprating of public sector pensions from RPI to CPI the GMB and other unions challenged the legality in the courts. How could it be right that pensions already being paid could be reduced by around 15% in value just at the whim of the Government? Unfortunately, the courts seem to take the view that the Government can do what it likes even if this amounts to taking money off pensioners just because they used to work in the public sector. It's not right and together with the other unions we will be considering the grounds for appeal. The decision has raised concerns that CPI inflation could become more widespread as a measure in the occupational pension sector. But research from the National Association of Pension Funds (NAPF) has indicated that most occupational schemes have RPI inflation written into the rules. The NAPF has found that about a quarter of occupational pension schemes are legally able to switch from RPI to CPI, but could not say how many have already done this or are seeking to do so. The NAPF has also predicted that uncertainty over inflation measures could arise for those who have deferred their pension from a job they had previously left, where RPI inflation may not be written into the scheme rules.