What appears clear by the responses so far is that nearly everyone wants to tax 'someone else', or have tax breals to suit them.
A swimming pool tax ffs. Really, that is just so much the tax of jealousy. It's not even a good indicator of real wealth.
The main aims should be to encourage investment by business. So many firms are sitting on huge balance sheets, but won't invest. Incentivise them. To create wealth, you need to encourage entrepreneurship/risk taking. However, when people are successful, the 'green eyed' envy people want them to be taxed at extortionate rates.
Have a real plan to close loopholes, where, for example, someone like Philip Green who (allegedly) has his dividends paid to his wife who is resident of Monaco, thereby avoiding paying tax in the UK. Bring the top tax rate down to 40%. It's widely accepted the high tax rates don't increase the tax take, as the rich will then work hardre to avoid payiung it. When Thatcher cut the tax rates early in here first term, the tax take increased, as it reduced the incentive to avoid paying tax.
Increase the tax threshold to help the lower paid.
Rationalise stamp duty on house purchases (similar to US above), but I would change the rules at £1m. I would add another bracket at say £2-3m of say 6% or 7%.