Want of knowledge and approval

An overview of the relevant law in relation to knowledge and approval of a Will.


In order for a Will to be validly created, the person making it (referred to as the “testator”) must know the contents of the Will and approve them.  Any interested person may apply to the Court for the Will to be declared invalid if they think the testator did not have this requisite ‘knowledge and approval’.

What does knowledge and approval mean?

Knowing and approving a Will essentially means the testator must know the contents of that Will, for example by reading it or having it read to them, and they must approve those contents.

If it later transpires after the testator has died that the contents were not as they wanted or expected, an interested person may seek to have the Will declared invalid by the Court, by making a claim for ‘want of knowledge and approval’.

This may arise in a number of different ways, often where there are allegations that a person has taken advantage of the testator.  This would include circumstances where the testator was too ill to understand the Will contents or where the Will was not read to or by them and therefore may have been different to that which they intended to execute.  Claims for want of knowledge and approval often overlap with capacity and undue influence claims - please see our guidance notes on these topics for further information.

Claims for want of knowledge and approval

If a testator has signed the Will, there is a presumption that they had knowledge and approval of the contents.  This presumption does not apply where the testator is blind, deaf and dumb or they have not signed the Will personally.  In such circumstances a different clause is used at the end of the Will which expressly states that the testator knew and approved the contents. 

The presumption can be rebutted where there is evidence which makes the circumstances surrounding the execution of the Will suspicious, for example where the Will is prepared by someone who benefits from it.  In these cases, it is for the person seeking to rely on (or propound) the Will to show that the testator did in fact have knowledge and approval of the contents of the Will.

Such a person will need evidence to prove this, for example statements from others that the testator wished to distribute their estate in this way.  It may be hard to gather sufficient evidence of the testator’s intentions, particularly given the possible length of time between the Will being executed and the testator’s death.

The evidence of the people who witnessed the Will could also be very important (if they are still alive and can be found).  If the Will was reasonably straightforward and the witnesses give evidence that the testator read it before signing, then it will be difficult to argue the testator did not know and approve its contents.


Another reason that a Will is not as a testator intended may be due to an error or mistake occurring in the preparation or drafting of the Will.

In such circumstances, an application to the Court can be made to rectify the Will so that the testator’s true intentions are reflected.  The Court will do this where, due to some clerical error or failure to understand the testator’s instructions, the Will fails to carry out the testator’s wishes.  Such an application should be made within 6 months of the grant of probate.

Where an error or mistake has been made by the solicitor or other professional who drafted the Will, another option may be to bring a claim against their firm for negligence.


As outlined above, a Will may be challenged if it is believed the testator did not know of or approve the contents.  There are other grounds on which the validity of a Will may be challenged, such as capacity, undue influence and improper execution.  We also have guidance notes on these which you may find useful.

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Every piece of content we create is correct on the date it’s published but please don’t rely on it as legal advice. If you’d like to speak to us about your own legal requirements, please contact one of our expert lawyers.

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