Mutual Wills – a binding promise?

Mutual Wills – a binding promise?

In the recent case of Legg and Burton v Burton, the High Court was asked to consider whether two siblings were entitled to equal shares of their late mother’s Estate on the basis that she had broken an express promise made to her late husband not to change her Will, under the doctrine of Mutual Wills.


Mr and Mrs Clark made mirror Wills in July 2000 (the “2000 Will”) leaving their Estate to each other upon the first death and to their two daughters (the Claimants) in equal shares upon the second death.

Mr Clark died in 2001 and having made no changes to his 2000 Will. His Estate passed to his wife in accordance with his Will.

Subsequent to her husband’s death Mrs Clark made a total of 13 Wills between 2004 and 2014 which departed from the terms of her 2000 Will. Mrs Clark’s final Will in 2014 left her Residuary Estate to her two grandchildren and one of their partners (the Defendants).

Is the doctrine of Mutual Will applicable here and how can you prove it?

In order to rely on the doctrine of Mutual Wills, it must be proved that there was a legally binding agreement between the parties that they will not changes their Wills. This type of Will is typically used by couples as an Estate planning tool to ensure that after the first death, their joint assets will be used in an agreed way, e.g. for the benefit of their children and/or step-children.

In the absence of contemporaneous documents to prove the existence of an agreement, it can be challenging to prove that there was a binding mutual agreement. These are often oral arrangements rather than a written contractual arrangement.

This case considered the role witness evidence has to play in Mutual Will cases and litigation cases in general. It is a well-known concept that memories can become less reliable over time and emotions and subsequent events or feelings can colour the way past events are recalled.

The reliability of memory evidence was a factor in this case. However, the key difference here was that the Claimants were able to link their memories to specific actions carried out by their parents and repeated notions. For example, in the Clark family it was regularly discussed that Mr and Mrs Clark had a strong belief in passing their home to their children and were very proud to have purchased their Council home. This notion was talked about generally by the family and the witnesses recalled examples, including being invited by their parents to attend when the Wills were signed.

The Claimants had also reminded their mother of the promises she made – these reminders had resulted in changes being made to subsequent Wills. The crucial difference in terms of reliability was that these beliefs and memories could be linked to and verified by physical actions.


The Court held that having expressly promised not to revoke their Wills at the time of execution Mr and Mrs Clark had made a legally binding agreement whereby Mrs Clark was unable to make a new Will after her husband’s death. The Claimants were entitled to equal shares of the Estate under the terms of the 2000 Will.

The Court concluded that the witness evidence presented was reliable as past events corroborated the memories.

This interesting case demonstrates that potential claims under the doctrine of Mutual Wills will continue to come before the Court. If the parties are seeking certainty there can be no substitute for expressly specifying if the testamentary document is intended to be either a mirror or mutual Will.