The £70k issue is really fascinating, at least partially due to the way people are reacting. Though I don't think it's a brilliant thing for McDonnell to have said politically, the conversations around it have hammered home just how screwed up the economy is. £70k is, statistically, a very large income, but there are myriad circumstances where someone earning isn't in any way rich. We are a society that has been almost trained to live by our means, or thereabouts, and what this tends to mean is that, even if someone on £70k lives a relatively lavish life style, they are still relatively insecure financially.
My personal inclination is that someone on £70k could stand to pay more, say, by lowering the 45% tax threshold to £70k. However, the problem I would have with the policy in of itself is that what it fails to do in any sense is to take from those who are really, genuinely wealthy. By taxing income from employment so aggressively, but by putting in place so many ways of earning (via assets and investments) that are taxed lower or barely at all, we entrench a system where those who are already wealthy don't have to give much more but those who are trying to become wealthy get absolutely screwed. This policy seems especially laughable when Labour are committing to continuing the triple lock on pensions. The system is tilted against the young enough already, is it not?
I am just entering my third year of employment but am on a high salary - I do not feel remotely wealthy as someone who is renting and saving to buy a home - but I would be willing to pay more tax. What I find very hard to accept, however, is someone like me paying more while those who accumulated their wealth in decades gone by can sit pretty with buoyant pensions, assets, and investments barely pay any tax. I'm willing to pay more - but I want to pay a fair share. Between student loans, national insurance and income tax, I lost 40% of my gross income last year. I'm okay with that percentage, but not when most much wealthier people don't pay anywhere near that rate on their total income.