Trust and marriage

We have a long-standing marriage contract trust created in 1947 by the then husband and wife in contemplation of their marriage and creating an alimentary liferent in favour of the wife.

Following her death the interest then passes to the husband and on his death the trust terminates and funds pass to the children.

Both spouses are still alive. Neither has any requirement for the income so the trustees have been instructed to sell the major part of the shares and as allowed by the trust deed pay over the cash to the children.

There will be very few investments left although the intention is to also sell those in the next tax year and again pay the proceeds over to the children. The trust will then be wound up.

What are the inheritance tax implications and are forms IHT100...