  The BaBar Collaboration has recently reported products of branching fractions
that include $B$ meson semileptonic decays into final states with charged and
neutral $D_{1}(2420)$ and $D_{2}^{\ast}(2460)$, two narrow orbitally excited
charmed mesons. We evaluate these branching fractions, together with those
concerning $D_{0}^{\ast}(2400)$ and $D_{1}'(2430)$ mesons, within the framework
of a constituent quark model. The calculation is performed in two steps, one of
which involves a semileptonic decay and the other is mediated by a strong
process. Our results are in agreement with the experimental data. We also
extend the study to semileptonic decays of $B_{s}$ into orbitally excited
charmed-strange mesons, providing predictions to the possible measurements to
be carried out at LHC.
