Form filling in the UK

Around seventeen percent of the New Zealand population identify as Maori according to the latest figures; and seventy percent are reported to be of European descent. It seems criteria in nz allows for these statistics.
Cultural heritage can cause qualms in the UK, especially when filling out forms which have been styled in order to make the form filler choose between being a British citizen and having another cultural background, the consequences of which result in differential treatment and possible discrimination.