But he is also an attack dog for the Ken Livingstone campaign, and today I received an email from the great man saying this:
"OK, I admit it. I get a lot of cabs these days. And let me tell you why I know Boris Johnson is in trouble. London cab drivers are moaning about his transport plans. You can't stop a London cabbie complaining about likely congestion in the Olympics or pot holes in the road".
"By the end of my weekly cab ride from Euston to Westminster my ears are usually ringing".
"And come the New Year taxi drivers will be joined by every Londoner that regularly uses the buses and Tube. When travellers swipe their oyster cards in January they'll be silently cursing Boris Johnson. Why? Because he has taken the decision to dramatically increase fares again."
"In January average fares in London will be going up 7% under Boris Johnson".
Boris' constant fare rises deserve to be criticised, but I'm not so sure about the reliance on black cab drivers as voices of concern for the average Londoner. These are people who already cost the earth for driving very short distances and are now demanding 15-20% higher fares or they boycott the Olympics. So not really on Londoners side after all.
And in any case what on earth is Tom Watson doing getting a cab, presumably at public expense, from Euston to Westminster - an almost direct route on the tube which would get him there in much less time and even less expense to us?
Tip to Tom: if you're going to talk about the tube, you might want to start using it.