LONDON: British Prime Minister David Cameron on Monday dismissed a new video in which five purported British spies are shot dead by masked Islamic State extremists as propaganda from a group that is losing control of territory in Syria and Iraq. “It’s desperate stuff from an organisation that really does do the most utterly despicable and ghastly acts and people can see that again today,” he said.  “But this is an organisation that’s losing territory, it’s losing ground, it’s, I think, increasingly losing anybody’s sympathy, and this again shows what an appalling organisation we’re up against.” British security officials are studying the video for clues about the identity of a masked man who speaks with a British accent on the video before shooting a captive in the head. The masked man, occasionally pointing a gun at the camera for emphasis, vows the extremists will soon invade Britain and establish Shariah law.