When selling a property, agents and solicitors involved will establish the id of the vendor and that they are legally entitled to sell. Without this proof, the sale would not go ahead.
When agents act for a landlord, they are required by law to disclose the landlord’s name, correspondence address and the address of the rental property. I see no reason why you should not follow this principle. It may also be worth establishing that the "landlord" is the legal owner and that the property is not being rented through a 3rd party.