15Variation or discharge by agreement or in accordance with express provision

1. Nothing in this subpart prevents a promise to which section 12 applies or an obligation imposed by that section from being varied or discharged at any time—

2. by agreement between the parties to the deed or contract and the beneficiary; or
3. by any party or parties to the deed or contract if—
   1. the deed or contract contained, when the promise was made, an express provision to that effect; and
   2. the provision is known to the beneficiary (whether or not the beneficiary has knowledge of the precise terms of the provision); and
   3. the beneficiary had not materially altered the beneficiary’s position in reliance on the promise before the provision became known to the beneficiary; and
   4. the variation or discharge is in accordance with the provision.

Compare

• s 6