From what I read this morning, it's rather debatable how much the 50p rate is likely to raise in tax revenue, and it is plausible that it would even cause a net loss. However, I suspect that many people would support taxing the rich more, even if it cost them money.
The Treasury estimate that the 50% rate will gain £2.4 billion, the IFS forecasts suggest it could be as bad as a £800 million cost. The Taxpayers Alliance claim it could be as bad as a £4.5 billion cost (though I think that very unlikely). In context, overall government receipts are £548 billion (after the June budget), so these figures are a fraction of 1% of overall income either way. Taxing the rich a bit more, or not, isn't going to either save the country from ruin or give us a land of plenty. On the other hand, the difference between IFS worst-case and treasury could pay for the whole Legal Aid program (as it was before yesterday), so it isn't completely without real relevance.
So, a poll, within the bounds of above expectations of the amount raised or cost being relatively small:
Would you support 50p income tax rate for the rich if it raised money overall? (i.e. increased income or services for everybody in the country).
Would you support 50p income tax rate for the rich if it cost money overall? (i.e. reduced income or services for everybody in the country).