You should report the loss or theft of your passport to the local police as soon as possible. You will need the crime reference details they provide for the Lost or Stolen Passport Notification form. You should also report the loss or theft to the UK Foreign and Commonwealth Office. You can obtain details of your local FCO office wherever you are by calling +44 (0) 20 7008 1500 or by visiting the FCO website. The FCO will issue you with replacement travel documents so that you can travel back to the UK.