Identifying UK citizens
I am trying to identify UK citizens in this dataset for my research. However, the nationality of the participant is not clearly defined. From the dataset, the only individuals who are asked about their country of citizenship are those who were not born in the UK. But this is assuming that all respondents born in the UK are UK citizens, which seems incorrect. I cannot use the "national identity" either because it is not the actual citizenship.
Would you kindly advise how I can identify among the respondents those who are UK nationals (=citizens)?