"the bottom line is that life expectancies have increased by 10+ years in a generation"
It is average life expectancies that have increased - largely due to less infancy deaths. It is a myth that people are living longer - it is actually that more people are living to the same age. But the Civil Service has actually shrunk in this time.
But of course if the Government says it's true then we it must be true - just like the fact that kids leave primary school barely able to read or write yet GCSE and 'A' levels results get better every year!
If you signed a contract to buy a car at a certain monthly payment and the company turned round half way through your repayment plan and suddenly said sorry but we want more now the I'm pretty sure you'd be upset.
Perhaps if we didn't spend so much on oversead aid or good old Gordon hadn't sold the nations gold reserves, then we wouldn't be having this debate!