I think you would have to be engaged by a solicitor who wants a valuation of the estate of the deceased whose will they are putting through probate.
It is just the same in a way as house clearance but the client is dead. In most cases there may be a will that makes specific bequests but where property is left at a house and there is no clear entitlement or the person actually died intestate, (no will) then the goods and chattells need to be valued and sold to create an estate and pay fees, death duties etc.
At least that is my guess lol