The main thrust of this paper is on real vacuum (single) Kerr-Schild (VKS) metrics. The conditions are given for real VKS metrics to have twistfree expanding principal null directions and to have Weyl tensors of Petrov type $D$. It follows that there are no twistfree type $II$ metrics i.e. no Robinson-Trautman ones. VKS metrics with twist either belong to the Kerr family or else are of type $II$. Non-expanding VKS metrics are of type $N$. The condition for a VKS metric to be of type $D$ leads naturally to a complex translation which has been used to obtain the Kerr metric from the Schwarzschild metric.