There are situations where probate is not needed, and this will depend on the type of assets owned and the nature of ownership. Where there is no land/property, involved probate may not be required to deal with relatively small amounts of money held in bank or building society accounts.
Even if there is land/property but this is jointly owned (as a joint tenant) and this passes automatically to the surviving co-owner(s), often between spouses or partners, then probate is not needed. Probate would be required to deal with land or property held as a tenant in common meaning that the share owned does not automatically pass on to the co-owner(s) on death.