There is one narrow, perilous route by which Rachel Reeves can successfully deliver her 26 November budget, and it runs right through government bond markets. But the current outbreak of Labour infighting driven by a flurry of pugilistic briefings from inside No 10 risks cutting that route off with two weeks still to go before budget day. Before news broke of an abortive leadership challenge, the chancellor had been carefully laying the groundwork for a tough statement, likely to include busting Labour's manifesto pledges