Thanks for your patience.
The registered proprietor of the property on the land registry title is ultimately who the landlord of the tenancy is.
They may have appointed an agent to act on their behalf in order to grant the tenancy, so that the “landlord” that you actually deal with during most of the tenancy is someone else. However, there is no central registry of tenancies so you are not likely to be able to find out.
So, I would write to the landlord/registered proprietor at the address for service noted on the land registry title and refer them to you problem. Ask for them to provide you with details of the agent (if any) appointed for the purpose of the tenancy agreement and take it from there.
The only other possibility might be to search on of the three deposit protection schemes to see if the deposit given for the tenancy is lodged with them. They may be able to confirm the agent for the landlord. The schemes are the three links first bullet pointed on the following page:
I am sorry that I could not have better news for you.
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