There is an old joke about former US President Ronald Reagan’s spokesman, a man called Larry Speakes. It was said that Reagan appointed Speakes to remind himself that Larry “speaks” for the president on TV, while Mr Reagan’s wife was officially to be called “Nancy Wife,” and his dog, Lucky, was inevitably “Lucky Dog.” Feeble jokes aide, Larry Speakes had a tough job. The White House press corps is a bear pit. Reagan, known as “the Great Communicator,” was master of the set speech, yet less able dealing with detailed questions from reporters. Sam Donaldson, a TV reporter, made his name by bellowing loud questions at Reagan, which the president usually affected not to hear and rarely answered. But what made Speakes’ job relatively simple was that everyone knew what Reagan stood for – low taxes, small government, big defence. Larry filled in the details. Now, for the first time, a British prime minister is to advertise for a Larry Speakes, an on-camera on-the-record spokesperson – in American slang, a "spox." At Westminster such briefings historically are anonymous. The new "spox" will be paid more than<strong> </strong>£100,000 (Dh480,790) and will probably be a woman. As prime minister Boris Johnson is regarded as having a "woman problem," meaning he has failed to promote enough women to top jobs, and so the betting says he will choose a female broadcaster. The speculation is all about "who?" but the real question should be "why?" Why would any qualified person want the job? Imagine, for example, you appear live on TV to cheerlead Mr Johnson's policies on coronavirus, defending the fact that England has the worst record of fatalities in Europe. Or how about Mr Johnson's "fantastic" opportunities for post-Brexit Britain? In reality we are preparing for endless traffic jams of lorries arriving from France, and possible shortages of perishable vegetables or medicines. And then there's the Big One – predictions for the worst economic recession in 300 years. Behind all this is what might be called the Trump Dilemma. What does an honest spokesperson do when faced with a barrage of allegations that your leader is lying, twisting facts, or simply blusters with no knowledge? Mr Johnson has been accused of all these things. Does an honest “spox” deny he is lying? Repeatedly? Press secretaries reflect their employer’s personalities. Germany’s Chancellor Angela Merkel has had just one for the past 10 years, the highly regarded Steffen Seibert, a man in tune with the calm manner of his boss. Donald Trump has had four hapless press secretaries in just three and a half years. In their eight year US presidential terms, Barack Obama had three, George W Bush, four. Richard Nixon had just one, Ron Ziegler, in five years. Ziegler is interesting because even as the Nixon administration unwound during Watergate, he remained loyal until the end. Joe Lockhart, Bill Clinton’s press secretary during his impeachment process, once told me that Mr Clinton’s staff – and he himself – remained loyal even though they thought their boss had behaved very badly towards former White House intern Monica Lewinsky. The reason for their loyalty was that Mr Clinton stood for something, changing America in a way they admired. They supported the plan, while being critical of the man. And that is the key problem for Boris Johnson. With presidents Reagan, Nixon or Clinton, the “spox” faced hard questions but the core of what those leaders stood for remained solid. A spokesperson cannot invent a coherent message for a leader who is himself incoherent or incompetent. A “spox” cannot invent an ideology for a leader whose principle goal is self-preservation. Mr Johnson notoriously wrote two versions of a newspaper column on whether he was for or against Brexit. Then he suddenly abandoned all his so-called “red lines” and accepted the long-rejected idea of a customs border in the Irish Sea. A “spox” will have to know that Mr Johnson is strongly Against Things until suddenly he is strongly For Them. Bringing coherence is not a communications battle on television. It is a private battle inside a leader’s head – a battle which Mr Johnson has not won. But perhaps there is another rationale for Mr Johnson employing a “spox.” He has come to believe he is charming when making amusing speeches to friendly audiences, but he is very poor at answering detailed questions in parliament. Perhaps this new spokesperson is to be Mr Johnson’s human shield, the person to sacrifice when it all goes wrong. Sean Spicer, Mr Trump’s first choice as White House spokesman, lasted just six months. Mr Johnson’s choice needs to be a credible person who nevertheless is willing to be pilloried so Boris Johnson can continue to be Boris Johnson. For a taste of what lies ahead, consider this week’s challenge – to defend Mr Johnson’s decision to award places in the House of Lords to people in his immediate circle. These include his own brother, plus a former member of the Revolutionary Communist Party which backed IRA terrorism, and a newspaper owner who is the son of a former KGB agent. Good luck. <em>Gavin Esler is a journalist, author and presenter</em>