  It is shown that a complex coordinate transformation maps the Taub-NUT
instanton metric to a Kerr-Schild metric. This metric involves a semi-infinite
line defect as a gravitational analog of the Dirac string, much like the
original metric. Also, it corresponds to self-dual dyon in electromagnetism
through three versions of classical double copy, one of them being a novel
nonlocal operator form. The relevance to Newman-Janis algorithm is briefly
noted.
