The Scottish Palestinian Solidarity Campaign staged a noisy demonstration on Tuesday outside the rescheduled lecture by Israeli Ambassador Ron Prosor at Edinburgh University.
The demonstrators, who estimated their own turnout at 100 - although police put it at more conservative 45 - chanted, "Shame, shame, shame" to members of the 200-strong audience leaving the university's McEwan Hall after the event.
A banner reading "Make Israeli Apartheid History" fluttered in the icy November breeze.
Mr Prosor's lecture, entitled "The Middle East Today: Regional Challenges, Global Implications", was originally scheduled for March but cancelled at the last minute amid "logistical concerns".
Shortly before the lecture, the mood among protestors was bullish. Mick Napier, chair of the Scottish PSC, yelled through a loudhailer: "Ambassador of child murder, ambassador of apartheid, ambassador of a rogue state."
The ambassador, however, met challenging questions head-on and said he had not been disturbed or embarrassed by the demonstrators.