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A secret trust is a trust in which the beneficiary is kept secret by not diclosed in the will. A trustee is appointed, who may be acknowledge in the will in the case of a half secret trust, or the trustee may be concealed as an outright beneficiary in the case of a fully secret trust

The will is a public document which can be inspected by anyone. A testator may wish to create a secret trust in order to prevent past discretions becoming public knowledge, for example by leaving property to a lover, or because he is not sure whom he wants to benefit under a will.

Secret trusts operate outside the will and as such they do not have to comply with the formalities laid out in section 9 of the Wills Act 1837. The rules for secret trusts are laid out in the case of Kasperbauer v Griffith [2000] WTLR 333, being the three certainties, communication to the secret trustee, acceptance by him and reliance.