Andy McSmith's Diary: "Prophylactic" Nick Clegg is no protection against Boris Johnson His contraceptive duties are not set out in the Coalition Agreement, but apparently they consist of protecting David Cameron's premiership from becoming pregnant with the kind of policies that only the Tory right would want to bring into the world. He's there to fulfil a very important ceremonial function as David Cameron's kind of lapdog-cum-prophylactic protection device for all the difficult things that David Cameron has to do. He's a kind of shield. He's a lapdog who's been skinned and turned into a shield to protect," the Mayor told the radio station LBC. His remarks suggest that Mr Johnson does not entirely believe the claim Mr Cameron once made that he has a "black book" of authentic Conservative policies he would like to have implemented if only the Liberal Democrats had let him. It implies that he had chosen to wear Nick Clegg to avoid fathering unwanted policies. If Mr Johnson were Prime Minister, we are invited to conclude, there would be no rubberised policy-making. The Mayor and the Deputy Prime Minister have a regular slot each on LBC, and have used them before to trade insults. Last June, Nick Clegg, who has a weekly phone-in, told listeners: "I'm going to call him Slacker Johnson. He's only on once a month. Mr Johnson retorted that Mr Clegg was an "idle bum" with spare time in his "ceremonial role as Lib Dem leader." This time, the Mayor began by claiming, with blatant insincerity: "I don't want to get into some sort of endless ding-dong with poor old Cleggers," before issuing the latest insult. And on Mr Clegg's 47th birthday too... Married to a mantra The reason politicians repeat key phrases with brain-deadening regularity is that they assume that almost all of the electorate are not listening almost all the time. But outspoken Labour MP Simon Danczuk thinks it's high time to shelve the practice. "We've already been told, from the very top, to intertwine "One Nation" into every policy statement we make," he complained in PR Week. I've come to believe the public is actively turned off by the torturous repetition of political mantras. He has called on his colleagues to strive for "authenticity," even at the risk of going off-message - advice that was rather lost on a Labour spokesman, who said: "We believe in Britain being a country where everyone plays their part and we'll continue to make the argument for One Nation Labour." Peace in our time For a short period today, the microphones in the House of Commons went kaput, and it became almost impossible to hear what Cabinet Office minister Greg Clark was saying. It made observers up in the gallery wonder how they coped in the old days, before microphones. When microphones first appeared in 1950, Winston Churchill insisted they be turned down when he delivered a speech in June 1950. Suddenly, the famous voice was too quiet for the listeners in the gallery overhead. There was a protest to the Speaker, and Churchill apologised.