I imagine UCL understand their course is fairly unique and that applicants will be applying to other universities as well. Presumably if you are interested in that area you'll be applying to some other courses which are somewhat related - there are many possibilities, ranging from e.g. law, criminology, sociology, social policy, cybersecurity and computer science to forensic science and chemistry/bioscience subjects.
Perhaps contact UCL and enquire about the matter and see what guidance they offer.