  The paper in the title [1] reports measurements of neutron scattering from
hydrogen in the 1-100 eV range of energy transfers, using the direct geometry
MARI spectrometer at ISIS. Stock et al claim that their measurements have
better or comparable energy resolution to those on the inverse geometry VESUVIO
spectrometer at ISIS. Most importantly the main conclusions of ref [1] are not
valid unless this claim is true: in particular the conclusion that anomalous
neutron cross sections measured on VESUVIO [2] are "the result of experimental
issues using indirect geometry spectrometers". We present here overwhelming
evidence that the energy resolution of the measurements in ref [1] is much
coarser than on VESUVIO. It follows that the conclusions of Stock et al are
unfounded. In reality the measurements of reference [1] serve mainly to
demonstrate that at eV neutron energies, direct geometry chopper spectrometers
have greatly inferior energy resolution to inverse geometry spectrometers based
on resonance foil methods.
