  A code $C$ in the Hamming metric, that is, is a subset of the vertex set
$V\varGamma$ of the Hamming graph $\varGamma=H(m,q)$, gives rise to a natural
distance partition $\{C,C_1,\ldots,C_\rho\}$, where $\rho$ is the covering
radius of $C$. Such a code $C$ is called completely transitive if the
automorphism group $\rm{Aut}(C)$ acts transitively on each of the sets $C$,
$C_1$, \ldots, $C_\rho$. A code $C$ is called $2$-neighbour-transitive if
$\rho\geq 2$ and $\rm{Aut}(C)$ acts transitively on each of $C$, $C_1$ and
$C_2$.
  Let $C$ be a completely transitive code in a binary ($q=2$) Hamming graph
having full automorphism group $\rm{Aut}(C)$ and minimum distance $\delta\geq
5$. Then it is known that $\rm{Aut}(C)$ induces a $2$-homogeneous action on the
coordinates of the vertices of the Hamming graph. The main result of this paper
classifies those $C$ for which this induced $2$-homogeneous action is not an
affine, linear or symplectic group. We find that there are $13$ such codes, $4$
of which are non-linear codes. Though most of the codes are well-known, we
obtain several new results. First, a new non-linear completely transitive code
is constructed, as well as a related non-linear code that is
$2$-neighbour-transitive but not completely transitive. Moreover, new proofs of
the complete transitivity of several codes are given. Additionally, we answer
the question of the existence of distance-regular graphs related to the
completely transitive codes appearing in our main result.
