Labour leader Jeremy Corbyn has got in a muddle over mortality, after claiming people in the UK were starting to die younger.

Corbyn attacked the Conservatives for ‘running our country down’. He said: ’Home ownership, opportunities for our children, wages and conditions at work, the NHS, care for our elderly, and now life expectancy: they’re all going backwards.’

Life expectancy is going backwards? That would be a surprise given how much we discuss how to deal with rising longevity.

Conservative chairman Patrick McLoughlin questioned Corbyn’s claim, saying it really was improving.

Corbyn would not be deterred. He said: ‘Whether the Conservative party chair can face the facts or not, life expectancy has actually fallen – by a year for 65-year-old women and six months for 65-year-old men – since 2013.’

Both Corbyn and McLoughlin were using the same figures: the Continuous Mortality Investigation, published by the Institute and Faculty of Actuaries (IFA).

This year the IFA revised down its projections for the average age people will reach.

But that does not mean life expectancies are ‘going backwards’ in the sense of people dying younger. It is simply projecting a slower future rise than had previously been projected.

Tim Gordon, chair of the CMI Mortality Projections Committee, told Channel 4: ‘The fall in projected life expectancy does not mean that individuals are dying younger. The latest CMI Mortality Projections Model – with typical inputs – projects that mortality will continue to improve and individuals will continue to live longer.’

Yesterday Corbyn seemed to have adjusted his statement tweeting his own facebook post which said: ‘Yesterday, Conservative Party Chairman Patrick McLoughlin claimed life expectancy isn't falling by pointing to mortality rates, which are improving but more slowly than before.

‘But the simple facts are - and we've checked this with independent health and actuarial experts - mortality rate improvements are slowing and life expectancy projections have fallen. One has contributed to the other.

‘It is a disgrace that life expectancy projections for those aged 45 and 65 have fallen and even more of a disgrace that the government is trying to cover it up.’

In reply, Steve Groves, previously chief executive of later life specialist annuity provider Partnership and current chair of Retirement Bridge, tweeted: ‘You need a lesson in the basics of mortality improvements and life expectancies, your interpretation is wrong. Life expectancy is improving.’

As someone who has to face constant questions over his own life expectancy, as Labour leader, Corbyn will surely be feeling red faced at this mix up.

Planners will be aware also how data on life expectancy is liable to change, so if the rate of improvement seems to be slowing now, there is no guarantee this trend will continue.