Sometimes you have to sympathise with David Cameron. Especially when various ministers and ex-ministers are lobbing political grenades at him from the safety of their Westminster bunkers while he is on the front line struggling to warm up an audience of tongue-tied young Mercedes-Benz apprentices in Milton Keynes.
Four seconds can seem an eternity if no one is asking a question. Yesterday the PM gallantly broke this excruciating silence with a stream of consciousness designed to overcome their shyness. "Who's going to win Formula One this year. Will it be Lewis Hamilton? What do you think?" More silence. "What about... anything you want to tell me about... this apprenticeship, what's good about it or anything you'd like to change about the balance between classwork and time spent here... How do you feel about that? Another question I really want to hear your views on is how much information you got at school. Do you feel when you were at school you were given a really good explanation of the choices? Anyone want to chip in on that?"
Mercifully someone did. But it had been slow work. For one thing it's hard to dominate an audience overshadowed by the gigantic, gleaming cab of an Arocs truck. There's something disconcerting about a vehicle of this size in a room full of people, like having an elephant in your kitchen.
But he was welcomed by the company's UK president and CEO, Marcus W Breitschwerdt, who declared just after midday with Teutonic precision: "Good early afternoon. We are very proud to have a very strong guest today, the Prime Minister of the UK." (As opposed to – say – Latvia.)
Asked about Nick Clegg's weekend claim that the Tories were like a "broken shopping trolley" lurching to the right, Cameron said: "I find with my own shopping trolley, once I put my daughter in there, it steers a pretty straight path and that's exactly what I'll be doing as Prime Minister of this coalition government."