I took out a loan in my first year of university. I failed and decided not to return. Instead I took up a series of menial and degrading jobs and consistently earned under the repayment threshold. I then started moving around a lot and even changed countries a couple of times. In all of this, the government seems to have lost track of me.
Mind you, I can't help but think that they aren't really looking that hard. I have a passport, driving license, a consistent history of paying tax, have frequently mithered my Member of Parliament on petty issues. Oh, and I've worked for multiple departments of central government and at one time had the privilege of being a named individual on a key interdepartmental policy document that was issued to the Treasury and Her Majesty's Revenue and Customs.