John Smith
For someone with a substantive doctorate, it is usual either to give "Dr" as the title (without a stop per normal British usage) or to list their degrees post-nominally, e.g. "Dr John Smith" or "John Smith, PhD" but not "Dr John Smith, PhD". Postnominals may be used with other titles, e.g. "Mr John Smith, PhD", "Sir John Smith, PhD", or "The Rev John Smith, PhD".