Doing the splits

We act for a non-resident settlement that has significant stockpiled gains from earlier years. The settlement owns a flat on a long lease in central London.

One of the beneficiaries of the settlement is currently in occupation of the flat and in past years we have obtained a one-year rental value and reported this as the benefit due under TCGA 1992 s 87 to establish the amount of gain that comes into charge for the year.

However what happens for 2010/11 given that the rate of capital gains tax changes during the year?

I note that for the temporary non-residence charge the gain is deemed to arise before 23 June 2010 and therefore to be liable to the lower rate of capital gains tax which applied then.

Is the same true for gains arising to...