Govt should have this data already
Don't EU citizens in Britain show their passport/ID card when applying for a NIN? I know the Spanish government knows my nationality. I've been made to go round to the town council to prove I'm still resident here or lose my EU treaty rights.
Getting employers to do Cruella De Vil's dirty work and using the party conference to turn the nastiness up to 11 only encourages more xenophobia by idiots.