Nah, it's just incredibly common amongst wealthy Britons to use schemes such as having your own personal Charity in one of the Channel Islands that pays for all your life and owns all your assets, so it looks like that person isn't at all rich.

Also the UK maybe uniquelly in the World has a Non-Resident Tax Status (for tax avoidance) which has nothing to do with the country one actually lives in, so a person can live in the UK and still declare him or herself as such and pay zero tax on income from abroad (and if you're rich it's pretty easy to set up a company abroad to channel all your income through).

(In fact Britain's billionaire Prime Minister was outted a few year ago as using such a schema)

Some of these schems had becom so prevalent that the Tories cracked down on the small fry (mainly self employed middle class) use of them too to avoid tax, but making sure ot was still fine for the rich (for example, Non Resident Tax Status now requires a year payment of 60k, so it doesn't make sense for somebody making, say 100k a year but it still does for those making millions)

In the land of the World's Money Laundromat most rich people avail themselves of the very abundant specialists in setting up schemes to make it look like they don't actually own any wealth, especially because it's risk free since none of the two main parties has any interest whatsoever in cracking down on tax evasion and avoidance by the wealthy.