https://www.theguardian.com/money/2018/may/29/im-buying-a-second-home-how-much-stamp-duty-will-i-pay
Unbelieveable that this buyer didn't realise he owed an additional £12,000 stamp duty until he opened the completion statement from the solicitor. The article details his byzantine but futile efforts at avoidance of the tax..... a "cunning plan" worthy of Baldrick, that completely failed.
Anyway, he bought a second house, whilst reclassifying his existing house as BTL and then designating the new house as his main res. So he's simply changing his main res? No....As the Guardian points out....you still own 2 houses mate, so suck up the 3% surcharge. You need to sell that BTL that was your main res. But it's too late now. Well I guess he has 3 years to sell and reclaim the 12k he just paid in tax......
As Del would say....what a plonker.