  We investigate a gauge extension of the Standard Model in light of the
observed hints of lepton universality violation in $b \to c \ell \nu$ and $b
\to s \ell^+ \ell^-$ decays at BaBar, Belle and LHCb. The model consists of an
extended gauge group $\mathrm{SU(2)}_{1} \times \mathrm{SU(2)}_{2} \times
\mathrm{U(1)}_Y$ which breaks spontaneously around the TeV scale to the
electroweak gauge group. Fermion mixing effects with vector-like fermions give
rise to potentially large new physics contributions in flavour transitions
mediated by $W^{\prime}$ and $Z^{\prime}$ bosons. This model can ease tensions
in $B$-physics data while satisfying stringent bounds from flavour physics, tau
decays, and electroweak precision data. Possible ways to test the proposed new
physics scenario with upcoming experimental measurements are discussed. Among
other predictions, the lepton flavour violating ratios $R_M$, with $M = K^*,
\phi$, are found to be reduced with respect to the Standard Model expectation
$R_M \simeq 1$.
