Johnson will produce his second major policy document this morning at 10.00 near St Pancras station - a fitting location not only because of its obvious transport connotations but also because its recent re-fit pleased the conservative school of architectural tastes.
What should we expect? Well, he'll want to produce a riposte to Livingstone's dismissal of what he said to Vanessa Feltz on Wednesday morning. Responding to a Chris from Cricklewood he agreed that the new-style Routemasters he aspires to replacing the bendys with would have to have conductors, and that the cost of this could easily be found by stopping TfL hiring so many consultants. Listen again from five minutes in and hear him say:
"I've looked at the expense of that. If all...suppose we were to replace every one of the 337 bendy buses with a new Routemaster it would cost eight million quid to have conductors on each of those buses, per year."
The following day on the same show Livingstone said that Boris's costings were all fine except that he'd left a nought off the end (listen again from four minutes in. He was a bit vague about bus numbers, saying there were "just under 400" bendys and that you'd need more than that number of new-style Routemasters to replace them (because they'd carry fewer passengers). He did a quick calculation about conductors: you'd have three shifts per day, pay each one about £25,000 p/a, well that's more like 80k.
I haven't done the sums myself or checked any numbers. You can see Team Ken's calculations here. They spoil things a bit by saying at the start that, "Johnson claims that it would cost just £8m to replace all bendy buses with new Routemasters" - he didn't, that was his estimated cost of their conductors - before arriving at a total figure, new Routemasters, conductors and all, of £110 million a year.
I'll be back to report on the launch this afternoon. Hope someone there's got a calculator.