Cannon v Hartley [1949]

Romer J thought Re
was authority for the proposition that equity would prevent the
enforcement of a covenant to settle only when:
1.  the plaintiff
was a volunteer and
2.  the plaintiff
was not a party to the contract.
So where a cestui que trust is a volunteer but also is a
party to the covenant, he can bring an action at common law for damages (but
not SP, as he is a volunteer)