  The TORCH time-of-flight detector is designed to provide a 15 ps timing
resolution for charged particles, resulting in $\pi$/$K$ particle
identification up to 10 GeV/c momentum over a 10 m flight path. Cherenkov
photons, produced in a quartz plate of 10 mm thickness, are focused onto an
array of micro-channel plate photomultipliers (MCP-PMTs) which measure the
photon arrival times and spatial positions. A half-scale
($660\times1250\times10$ mm$^3$) TORCH demonstrator module has been tested in
an 8 GeV/c mixed proton-pion beam at CERN. Customised square MCP-PMTs of active
area $53\times53$ mm$^2$ and granularity $64\times64$ pixels have been
employed, which have been developed in collaboration with an industrial
partner. The single-photon timing performance and photon yields have been
measured as a function of beam position in the radiator, giving measurements
which are consistent with expectations. The expected performance of TORCH for
high luminosity running of the LHCb Upgrade II has been simulated.
