David and Ed Miliband's courteous rivalry appears to have broken out into full-blown fight for the Labour leadership.
The two front runners' truce disintegrated after David gave a speech calling for Labour to not retreat into its 'comfort zone' on the left, seen as a direct attack on Ed Miliband, who has recently been attracting the greater media attention.
The younger Miliband responded to his sibling's attack with a cutting attack on New Labour, which David Miliband is seen to represent.
Even for committed followers of politics, the contest, in which Ed Balls, Andy Burnham and Dianne Abbott are also standing, had been largely uninspiring. This week's hostilities are a sign it is hotting up before ballot papers are mailed out, however.