There is a cold reality about cuddly uncle Ken which deserves serious examination: he is a ruthless political operative who will sell out everyone, including his own party, to win.
But Ken is not just a divisive figure, he was also a sinister Mayor, presiding over an wildly dysfunctional London Development Agency, controlling policy for London through a cabal of advisers calling themselves 'Socialist Action' and getting chummy with divisive and radical islamists including Yusuf al-Qaradawi.
In the build up to the 2008 election, his mask of plain-spoken decency began to lift which, at the time, alarmed several cabinet ministers. Now Labour have entered opposition, their memories seem to have been wiped.
That's typical of the concern that Livingstone causes in his party. What else would you expect from a man who, as Andrew Hosken points out in his model biography of the former Mayor, found inspiration in The Godfather?
Livingstone once said that Mario Puzo's epic was "a much more honest account of how politicians operate than any of the self-justifying rubbish in political biographies" and, in company, quotes the Don with tiresome regularity.
If you want a working definition of "the old politics" on which Cameron sometimes stoops to generalise, Ken is it.
Labour should have moved on, it has not. The old forces still grip it. That should be no small concern to a reforming Labour leader.