According to TfL's annual report Mike Brown's salary was £310,734 last year.
He is managing director of both London Underground and London Overground, which together carry more passengers than the national rail network.
According to the Standard today, based on an FOI request from @MayorWatch:
London Underground managing director Mike Brown did not claim for any taxis during 2010 and 2011. His total expenses for 2010 came to £112 and in 2011 £710.95.