Left: Isolated-photon differential cross section measured in \PbPb collisions at \snnfive for the 50--90\% centrality class, for $R=0.2$ (scaled by a factor 10) and $R=0.4$ (not scaled). Error bars and boxes are the statistical and systematic uncertainties, respectively. The bands correspond to NLO pQCD calculations with JETPHOX, for \PbPb collisions calculated for the 0--100\% centrality class but scaled by \Ncoll. Right: Ratio of data over JETPHOX NLO pQCD calculations for $R=0.2$ (top) and $R=0.4$ (bottom). The bands centred at unity correspond to the JETPHOX NLO pQCD calculation uncertainties. The normalisation uncertainty of 2\% is not included in the left panel but it is shown as a grey box in the right of each frame around unity.