Brain Cooke is the chairman of TravelWatch, the independent London Transport watchdog.
He has long experience of representing the interest of passengers to transport companies and of monitoring TfL and Ken Livingstone, chair of its board.
In today's Ken-hating Evening Standard, he's spoken out in favour of Boris Johnson and been rather rude about the mayor.
"Ken has paid lip service to real consultation on a whole raft of issues," he says, "and I don't believe Boris will have the arrogance of the 'Ken knows best' policy."
Cooke claims that, "TfL and Ken Livingstone are so joined at the hip that the board seem frightened of critiquing," and that there is "strong evidence that the current mayor has played with both tube and bus fares for his own political aims".
His intervention is the more inconvenient for Livingstone in that he supported the present mayor at the previous two elections.
And this is no overnight conversion. Cooke was billed to appear alongside Johnson at the launch of his transport manifesto on March 3. TravelWatch is supposed to be apolitical, and you could tell that someone had spotted that this was a problem when the note sent to journalists advising them about the launch was amended to say that Cooke would be appearing "in a non-political capacity," to present the "independent views of London's transport users". In the event, he didn't appear at all.
Well, now he's laid his political cards on the table just three days before the election. The Standard also reports that:
"The chairman's decision to speak out is sure to trigger a row among TravelWatch members. The watchdog's board is politically independent but includes councillors and ex-councillors from the three main parties. He emphasised that he was expressing personal views, which were 'not necessarily the views of TravelWatch', and has taken leave until Thursday's poll."
Talk about hit and run.