London Mayor Boris Johnson said a Labour Government "is the greatest barrier to competitiveness" in the UK.
However, when he asked what the greatest threat was during his conference speech, a silence fell over the hall.
As someone shouted out that it was visas he exclaimed, "Not visas! Much worse than visas. What is the greatest threat we face? Come on folks - pay attention!"
Eventually a delegate got the correct answer and was met with applause and cheers.
More top news
Hacking group Lizard Squad claimed responsibility for the attack which left thousands struggling to access their accounts for hours.
Three men broke into a house on Christmas morning but when the owner said he had no money they took his pets instead.
ITV News' John Irvine witnessed the devastation wrought at Banda Aceh ten years ago. Now, a long-sought revival is underway.