Will Smith

I am a dual UK/US national, resident in UK since 1993 and I bought my current home, my principal residence, in 1999. I understand that if I sell my home no UK tax on capital gains is due. However, the US taxes capital gains on sale of one’s principal residence and 25 years of gains on a London home would be well in excess of the personal allowance on the sale. Can you confirm this situation is not covered by the dual taxation treaty and I would be liable for the full amount of US tax even if not taxed on the sale in the UK? Conversely, the US does not tax capital gains on the sale of a rental property if the proceeds are reinvested in another property within a specified period. If I were to vacate my home and let it out for a number of years before selling it, would I then become liable for UK capital gains tax on the sale of the property? Is this situation also not covered by the dual taxation treaty?