The Henley and partners analysis isn't very good, but nor is this, both are from biased sources. It seems to amount to "that isn't a large proportion" rather than looking at the trend.

Dan Neidle[1] and the FT[2] have already done much better debunking of it, although that doesn't mean there isn't truth to it, just that Henley and Partners's report doesn't prove anything.

Chris Giles at the FT did a good summary[3]

[1] https://taxpolicy.org.uk/2025/07/27/henley-partners-milliona... [2] https://www.ft.com/content/28ebf57d-af22-48a0-91b9-880e3f1fb... https://archive.is/w6New [3] https://www.ft.com/content/0a24be5e-395e-43db-a91f-4b4f02d99... https://archive.is/Le05V