Quite funny to see the Daily Mail attempting to show the geography of the cemetery in Tunis, and the various graves of Palestinians. Apparently, there was a red canopy which ran alongside Black September graves, and Corbyn was definitely nearby. This all seems a bit, "you were in the same room as alleged terrorist X".
Ironically, Netanyahu has probably helped Corbyn by attacking him, since Israel has killed thousands of Palestinians in recent years. Who mourns them?