  The photoproduction of isolated photons has been measured in diffractive
events recorded by the ZEUS detector at HERA. Cross sections are evaluated in
the photon-proton transverse-energy and pseudorapidity ranges 5<ET(gamma)<15
GeV and -0.7<eta(gamma)<0.9 inclusively and also with a jet with transverse
energy and pseudorapidity in the range 4<ET(jet)<35 GeV and -1.5<eta(jet)<1.8,
using a total integrated electron-proton luminosity of 374 pb-1. A number of
kinematic variables were studied and compared to predictions from the RAPGAP
Monte Carlo model. An excess of data is observed above the RAPGAP predictions
for z|P(meas)>0.9, where z|P(meas) is the fraction of the longitudinal momentum
of the colourless "Pomeron" exchange that is transferred to the photon-jet
final state, giving evidence for direct Pomeron interactions.
