@JenniferAnistonfan what is yours or your mums actual concern? She signed up to this agreement 7 years ago knowing she wasn’t going to move in - so what has changed to cause all of this concern?
You say she has checked her credit file so it doesn’t sound like there is a problem there.
Then there is the subletting which the landlord doesn’t know about. If the landlord finds out he may apply to terminate the tenancy, which would solve your mums problem (which is if her own making). Is that why you want the landlords details; so you can inform him of the subletting? Granted if your uncle refused to move and the landlord took the tenants to court to evict, that would include your mum as a named tenant.
The only other thing I can think of is that your mum wants to move/borrow money and is concerned that a financial link to your uncle will show up - but you can link at financial associates in your credit report.
i just want to understand what is concerning your mum now which wasn’t a concern to her 7 years ago.