Tony Benn's astute political diaries illuminated the age in which he lived, says Chris Mullin http://telegraph.feedsportal.com/c/32726/f/579309/s/3832f37c/sc/7/l/0L0Stelegraph0O0Cnews0Cpolitics0Clabour0C10A69820A90CTony0EBenn0Ethe0Eradical0Ewho0Enever0Elost0Ehis0Epassion0Bhtml/story01.htm