GOV.UK
Undisclosed Partners: Respecting Customer's Privacy
In all your contacts with customers you must always be aware of Human Rights issues, and of the need to respect the customer’s privacy. It is particularly important that you adopt this approach in any discussions which may touch on their private life.
You should avoid any impression that you are examining the customer’s home or household for signs of any such relationship. You must not ask about the customer’s sleeping arrangements in an attempt to find out whether s/he shares a bedroom with another adult.
Customers may however volunteer information of this kind when, for example, confirming the number of children who live there; describing how friends or relatives sometimes stay to help out with childcare or explaining that their ex-partners stays in the spare room whenever they come to visit the children. If the customer simply says their partner stays overnight when they come to visit or care for the children you must not ask where they sleep.
You should not normally ask customers about the number of bedrooms in their house but if the customer has suggested that an adult who lives in the house is a paying lodger, it is reasonable to expect the lodger would have his/her room rather than sleeping on a sofa or floor.
In the circumstances it will be appropriate to ask how many bedrooms there are and what room(s) the lodger occupies, and to test the answer in the light of other information/evidence. The number of bedrooms and the ages/sexes of the other occupants of the house will be relevant. For example the customer may live in a 3 bedroom house with 2 children, a boy of 12 and a girl of 16, and it will be reasonable to ask what arrangements have been made so that the lodger can occupy his/her own room.
It is important that any questions you need to ask should be directed at establishing the room the lodger occupies and their relationship with the customer and not at establishing who the customer sleeps with.