As one person close to the Tory leadership reflected to me on Friday, Boris’s interventions on Europe and 50p have caused Cameron problems because they have been immediately amplified by the right and Cameron has been conscious that most of his party agrees with Boris not him on the issue. But pretty much no one on the right agrees with Boris on housing benefit so his remarks fell on deaf ears.
There is undoubtedly a space in British politics for a voice to the right of David Cameron. When Boris is filling that space he is a danger to Cameron. But when he is not, it is far easier for Cameron to put him back in his box.