My employer in the United Kingdom has been requested by a third party (whom we, the company, work for) that all employees complete a security related interview involving personal questions such as if we have any issues in our marriage, if we have any problems with car/house loans etc., If we have problems with alcohol or drugs outside of work and other personal questions.
This is for the benefit of the 3rd party company and was not mentioned in our original contract unless there is a catchall clause covering it. We have all worked here for more than 3 years.
The answers will be recorded with a summary sent to the 3rd party confidentially and records kept confidentally by our HR department at our company.
Is this legal in the UK? There has been an implication that it wouldn't be acceptable to refuse to answer questions.