Charity and cash

We act on behalf of a trust. Following the recent death of the life tenant the trustees are required to pay some relatively small 'legacies' (fixed cash amounts) to individuals and then to hold the remainder for distribution to charities at the trustees' discretion.
Whilst the trust benefited from a capital gains tax free uplift on the death of the life tenant the investments have increased in value since then.
As the trust fund is not held entirely for charitable purposes until the legacies have been paid would any gains realised before the legacies have been paid be chargeable to capital gains tax?
Furthermore would gains realised after the legacies have been paid be chargeable to capital gains tax if realised in the same tax year in which the legacies are paid i.e. in a tax year throughout which the trust fund was not held entirely for charitable...