Like me, you may been labouring under the illusion for some time now that what lay behind the current passion for reform of Public Sector pensions was that the country simply couldn't afford them - especially given the fact that people are now expecting to live much longer and therefore draw on that pension for longer.
And if so, then again, like me you may be surprised to learn this isn't true. Remarks like David Cameron saying "The reason we can't go on as we are is because as the baby boomers retire – and thankfully live longer – the pension system is in danger of going broke", may have led you to that conclusion, but's not the case. This is ably demonstrated by this excellent analysis and interview by Evan Davis, and if you want proper details you could do worse than read this piece on False Economy (though be warned, it isn't exactly a cool, objective look at the issues - but it is very well researched).
If you don't want to read all that detail or listen to the interview, the summary soundbite is that public sector pensions will actually drop as a % of GDP over the next 30 years, even without any of the current reforms.
So, if the reforms are not driven by affordability, what are they driven by? The answer - allegedly - is 'fairness'. The argument goes that Public Sector pensions have been protected over recent years, private sector pensions have dropped dramatically, and as the private sector taxpayer funds the bulk of the public sector pension pot, this isn't fair.
Personally, I don't buy this argument. As a private sector worker, I'm quite happy to fund Public Sector pensions, even if my own pension pot is dwindling, partly because they are just plain worth it, and partly because that was the deal we did to get workers into the public sector in the first place. But I know others feel differently.
But whichever side you take, don't do it on the grounds that it's unaffordable ( or as it's now being described, untenable). Because it simply isn't true.