The pound tanked and gilts soared this morning as the markets reacted badly to the possibility of Andy Burnham becoming prime minister.The yield on 30-year UK Government bonds, also known as gilts, lifted to fresh recent highs, rising by 16 basis points to 5.821 points, the highest in almost three decades.Ten-year gilts were also suffering another sell-off, with yields firmly above 5 per cent, up 16 basis points to 5.155 per cent.The pound was down as much as 0.4 per cent against the US dollar, before settling around 0.2 per cent lower at 1.334 US dollars.Political concerns added to worries over the inflation outlook amid the Iran war to send London's blue chip FTSE share index sharply lower. It came as allies of Sir Keir Starmer fought a desperate rearguard action to try to protect the lame duck Prime Minister.Mr Burnham last night launched the first stage of what is seen as a campaign to take control of Labour and the country that could put him in No10 by the summer.Housing Minister Steve Reed insisted Sir Keir was 'fine' and getting on with the job in hand as he toured TV and radio studios today after a 'terrible week'.And he warned Mr Burnham and any other Labour figure planning to challenge the PM against mimicking the previous Conservative government and 'doomscrolling' through leaders in a short period.But his attack came as Sir Keir's grip on power appeared to have weakened beyond saving.In an astonishing turn of events last night Greater Manchester Mayor Mr Burnham confirmed he would seek to return to the Commons, a move seen as a precursor to a leadership challenge.