My mum is not very well at the moment, and a few years ago she made a will.

Because she is ill at the moment, she asked me if the will is still legal as one of the witness has since died.

Does anyone know ?

I would think it is still legal, if it was properly made out in the first place. You can't be expected to make a new will out every time, or even keep track of witnesses.

If it's kept with a solicitor, your mum could ask them to double check it, and then if she wanted any amendments making they could do that too.

Hope you mum's better soon.

Death of a witness does not invalidate a will.

Thank you, my mum will be relieved.

The help is much appriciated.

from a will guy, the will is still valid.
however if the "executors" all predecease your mum it can cause some holdups with probate.otherwise your all ok.