“Probate” is the process of proving that the Will of the deceased is legitimate, and a “Grant” is the Court’s seal of approval. It acts like the “deeds” to the deceased’s estate, without it, the Executor may have trouble proving that they “own” it.
Executors have authority and power over the assets of the deceased, and this stems from the Will itself, but for many asset holders (banks, share registrars, HM Land Registry) there is too much at stake to trust the Will alone. They need the Executor to give formal evidence, before the Court, that this is the Last Will.
Over the years the visibility of the Court has rather diminished, but it is still at the centre of the process. When an Executor is told that they “need a Grant”, then they need to give formal evidence (now a matter of completing a form, often online, and signing a statement of truth) that the Will is indeed the Last Will. Other matters of fact are also required by the Court, and during the process, the Court may ask for more evidence to be given.
The statement of truth has replaced the sworn oath, but a statement of truth is still evidence given in Court, and falsehoods can be punished.
If all is well, the Court will approve the Executor’s application and will seal a Grant of Probate naming the deceased and the Executor. This provides the asset holder with the comfort they need to be able to hand over the deceased’s property.
The responsibility for the asset then passes to the Executor.