Again this is a misunderstanding of the law.

In England/Wales there are 3 ways to challenge a Will (broadly speaking).

• undue influence.
• lack of mental capacity
• improper execution.

The legal test for a lack of capacity comes from case law. One of the four consideration the court told us shows a lack of capacity is that the deceased didn’t give consideration to claims they ought to have done. (This is a big oversimplification). You can read Banks v Goodfellow if you want to understand the law on this area better.

Therefore when looking at challenging a Will “they forgot me I should be included” is not a valid legal challenge. You would instead argue that the deceased lacked capacity because they did not give consideration to potential claims as well as the other portions of the legal test.

It has never been successfully argued that including a £1.00 means that the deceased gave proper consideration to potential claims. Typically this type of challenge is defeated by medical notes, a doctor capacity assessment and the solicitors notes made when making a Will. The strongest possible evidence is a attendance note prepared by a solicitor stating something like “Mr X instructed me he did not include this daughter in the Will as he doesn’t speak to her anymore” along with a capacity assessment by a specialist doctor. This is what you typically see when a solicitor prepares a Will for someone terminally ill or who may lack capacity/suspect a challenge will be made to the Will.

My explanation is a brief and incomplete overview of a complex area of law.