David Cameron delivered what could be one of the most important speeches today, setting out his plan to curb immigration. Unfortunately for the prime minister someone set off the fire alarm in the JCB factory he had chosen as the venue.
Many politicians may have unwisely decided to doggedly continued with the ringing in the background, however Cameron decided to wait for someone to switch it off.
His plans to change EU migration rules had "clearly sent of alarm bells in the European Commission", he joked. "I'm glad it has had that effect".
Taking a sip of water while aides scrambled to return the peace, he told reporters: "I once made a speech in a car plant where they didn't stop the car plant operating, so I had to speak louder and louder as more cars came off the production line."
In his speech, Cameron gave his strongest hint yet that if his planned re-negotiation of Britain's relationship with the EU fails he would consider arguing in favour of exit. "I rule nothing out," he said. "The British people will not understand, and frankly i will not understand, if a sensible way through can not be found."
In a message for other EU leaders, as well as British voters, Cameron said the UK's concerns about immigration "are not outlandish or unreasonable". He added: "We deserve to be heard and we must be heard."
However the prime minister reminded voters that immigration had been a good thing for Britain. And in a rebuke to Ukip and Nigel Farage, as well as eurosceptic backbench Tories, he said: "These who promise you simple solutions, they are betraying you."