  The study of neutrino oscillation at accelerators is limited by systematic
uncertainties, in particular on the neutrino flux, cross-section, and energy
estimates. These systematic uncertainties could be eliminated by a novel
experimental technique: neutrino tagging. This technique relies on a new type
of neutrino beamline and its associated instrumentation which would enable the
kinematical reconstruction of the neutrinos produced in $\pi^{\pm} \to
\mu^{\pm} \nu_\mu$ and $K^{\pm} \to \mu^{\pm} \nu_\mu$ decays. This article
presents a proof-of-concept study for such a tagged beamline, aiming to serve a
long baseline neutrino experiment exploiting a megaton scale natural water
Cherenkov detector. After optimizing the target and the beamline optics to
first order, a complete Monte Carlo simulation of the beamline has been
performed. The results show that the beamline provides a meson beam compatible
with the operation of the spectrometer, and delivers a neutrino flux sufficient
to collect neutrino samples with a size comparable with similar experiments and
with other un-tagged long-baseline neutrino experimental proposals.
