Whatever he called the policeman, it appears to have been uncalled for. Not only was it wrong but to do it at that particular time was simply crazy. I'm afraid it is not up to the standards one would expect from such a senior position and he should "fall on his sword".
Cameron has a problem of course in appointing someone to such a senior position who can do a thing like this again calls his judgement into question. I think it is pretty clear by now that his judgement is pretty bad on many things.