  We simulate a self-gravitating, turbulent cloud of 1000 Msol with
photoionization and radiation pressure feedback from a 34 Msol star. We use a
detailed Monte Carlo radiative transfer scheme alongside the hydrodynamics to
compute photoionization and thermal equilibrium with dust grains and multiple
atomic species. Using these gas temperatures, dust temperatures, and ionization
fractions, we produce self-consistent synthetic observations of line and
continuum emission. We find that all material is dispersed from the (15.5
pc)$^3$ grid within 1.6 Myr or 0.74 free-fall times. Mass exits with a peak
flux of $2 \times 10^{-3}$ Msol/yr, showing efficient gas dispersal. The model
without radiation pressure has a slight delay in the breakthrough of
ionization, but overall its effects are negligible. 85 per cent of the volume,
and 40 per cent of the mass, become ionized -- dense filaments resist
ionization and are swept up into spherical cores with pillars that point
radially away from the ionizing star. We use free-free emission at 20 cm to
estimate the production rate of ionizing photons. This is almost always
underestimated: by a factor of a few at early stages, then by orders of
magnitude as mass leaves the volume. We also test the ratio of dust continuum
surface brightnesses at 450 and 850 micron to probe dust temperatures. This
underestimates the actual temperature by more than a factor of 2 in areas of
low column density or high line-of-sight temperature dispersion; the HII region
cavity is particularly prone to this discrepancy. However, the probe is
accurate in dense locations such as filaments.
