57. Matters to be proved before rectification is granted.

To justify the court correcting a mistake in an instrument, the evidence must be clear and unambiguous ('convincing proof'1) that a mistake (whether of fact or law2) has been made in recording the parties' intention3, what that intention was4 and that the alleged intention to which it is desired to make the agreement conformable continued concurrently in the parties' minds down to the time of the execution of the instrument5. In considering the intentions of a collective body (such as a group of trustees or a committee of a board), it is their collective intention which is relevant for