I am in the fortunate position of being a landlord. We have just changed the agents that look after the house. As well as signing a contract with the agents they required a lot of extra details. Information like who supplies the gas and electric, which telephone company is used, what is the number of the gas safety certificate was not a surprise. What was a surprise was the requirement that we supply tax reference and national insurance numbers. When we questioned it, we were told that HMRC demands this information from the agents. We can only presume that this is so that they can confirm independently that what I state on my tax return is correct. If they want to go to that trouble they can do the bloomin' tax return for me. Still, it certainly lends weight to this report.
You don't need to worry though because you are not a landlord. Well, perhaps you do according to this.