The story of the blogger and calculator

A blogger and a calculator have helped to shape a serious debate about who is competent to lead a great city like London.

In a BBC interview last week Boris Johnson claimed that the cost of his policy of bringing back buses with conductors would be £8 million a year. This Monday his transport manifesto gave a pledge to introduce a new bus 'with conductors'. He repeated his claim that it would cost £8million on 4 March. Ken Livingstone argued the cost of this policy is grossly understated.

Who was right?

So the journalist and blogger Dave Hill decided he would take it upon himself to look into the rival claims and cast his independent eye over the facts. He dug out the facts directly and assembled the figures. Here's his verdict:

Boris Johnson has underestimated the cost of his bus policy by at least £100 million per year. That would mean a bus fare increase from 90p for a single journey to £1.05, or an increase in the cost of a weekly bus pass from £13 to £15.

After two decades of neglect, a £1 billion a year Tube invest programme is underway. Ken's expanded bus services so that 90 percent of London households are within 400 metres of a bus stop. We've expanded investment in cycling, resulting in an 83 percent increase in cycling levels over the past five years.

And although people now take it for granted, he's brought in Oyster cards, abolished bus and tram fares for children and defended the Freedom Pass from Tory attacks that it is a 'stealth tax.'

So before Ken Livingstone launches his transport manifesto, what do you think are the big issues in this area?