On a £20million property? It'll be owned by a shell company in the Vigin Islands or some other tax haven & only the ownership of the company will ever change hands so no stamp duty will be due in the UK.
Yes, this is iniquitous. Stamp duty should clearly be replaced by a better targeted land tax, but good luck getting any UK government to make that change...
I believe this isn't true any more. Legally, stamp duty will be due at 15% in this case.
Of course, whether this is enforceable, whether the authorities make any effort to enforce this (as opposed to it being a nice sounding law to appease the public), and whether the people involved actually report these transactions are entirely different matters, and I wouldn't be optimistic.
Only for newly built properties - the transfer into corporate ownership attracts 15% duty. However, properties that are already owned by offshore companies care unaffected.
I agree that there are probably ways round the new rules too: The tax laws in this country are so complex that those who can employ the best accountants and lawyers can often simply out argue the Inland Revenue.
However, if you're not being paid to live there in return for some service there's no employment contract and no income tax to pay. At least that's my understanding of the situation.