I believe (quote in the paper recently but hey what do they know) that only 8% of Britons earn over £40,000 pa. Since almost everyone I know earns in the 40,000 to 70,000 bracket then the % earning over 70,000 is likely to be much smaller. However, that does not take away from the fact that to describe someone earning over 70,000 as High Net Worth is laughable.
A High Net Worth individual is someone who earns that much bank interest on their current account in one month.