How do the authorities determine start of residency in UK for a UK passport holder

• The reason for the question is I want to swap my non-UK drivers licence for a UK one. I know I can do this within 1 year of being resident here. Is my last entry date into the UK a valid date to use for the date I became resident?

  11 Lug 2009, 01:03 UKbornNZex-pat