Testamentary trusts have been used in Wills for a long time.

A testamentary trust is a trust established after a person dies to hold assets for the benefit of the beneficiary. Instead of the beneficiary receiving assets directly from the estate in their own name, the assets go into a testamentary trust controlled by an appointed individual known as the Trustee. 

This may be beneficial for a number of reasons, including:

• taxation minimisation, especially when distributing to minors
• protection of estate assets against creditors
• possible protection of estate assets from a relationship breakdown.

Using a testamentary trust within a Will can allow greater control of the assets when they're distributed to the beneficiaries. It can also provide taxation advantages and protect the assets in certain situations.