A wealth tax does not need to be 10%. That's a silly idea, intended to frighten the readers. There is a vast amount of wealth in this country, and it is untaxed.
So the average worker pays income tax, and the wealthy person doesn't pay wealth tax.
Most of the wealth in the UK is now in Property and in Private Pensions.
Neither of them are easy to hide, and there are ways of valuing them.
It would be much more difficult to value your collection of porcelain miniatures or your Victorian personal appliances, and much easier for you to hide them, so not a good candidate for taxing.
If there was going to be a tax on property, it would probably be a version of Land Tax, which has been discussed as a replacement for Council Tax and Business Rates. It is usually proposed that the amount of money raised should be the same as Council Tax and Business Rates gather, so it would not be an "increase" in the tax take. But it would probably not be capped in the same way as House Bands are for council tax, so it would be resisted by multi-billionaires such as Lord Harmsworth; and removing the cap would mean that it could raise more money, should this be necessary, or, alternatively, it could lead to a reduction in tax on those of us who are not multi-billionaires.