But don't young people grow old, have children that need educating, need health services and then become pensioners themselves?Ehem..
Raising the retirement age to 70 does not in any way help the financial imbalance we need to address now
The tax we pay today only funds ( or rather fails to fund ) the pension costs of pensioners right now
The money you, I, or anyone pays into the tax system does not get put aside for your, mine or anyone else's pension
The UK needs a whole lot more young people, in work, paying tax - Fact
My worry is that growing the population to solve our problems is a kind of Ponzi scheme especially when we have seen successive governments not ensuring that enough housing and public services have been provided for the growth in population that we have seen over the past 20 years and having no confidence in them to do so over the next 10 or 20 years. It's all very well aspiring to have an economy as big as Germany but not at the price of ending up with a population above 80 million.
That said, there is strong reasons to have immigration to rebalance the demographics of the UK and to meet the skills shortage, but that should be achieved by having a controlled immigration policy that allows just that and not the free for all we have at present.