What is probate?
Probate is the legal process of proving a will and obtaining authority to deal with someone's estate. It confirms who may collect assets, settle debts and distribute what remains. Not every estate needs it — small estates and assets held as joint tenants often pass without a grant.
The process runs roughly in sequence: identify and value everything owned and owed, report to HMRC and pay any inheritance tax due, apply for the grant, collect in the assets, settle liabilities, then distribute and account to beneficiaries.
Inheritance tax generally has to be paid before the grant is issued, which creates the well-known cashflow problem — the money is locked in the estate the grant is needed to unlock.
The slowest phase is almost always the first. Establishing what actually existed — which providers, which policies, which accounts, which property — routinely takes longer than the legal process that follows it. A maintained record collapses that phase from months to days.