John McCain, the Republican frontrunner in the race for the White House, today abruptly cancelled a trip to Europe that would have involved dropping in on Gordon Brown. Brown's spokesman announced this morning that McCain would visit No 10 on Friday, though he stressed that this did not imply any prime ministerial endorsement of the Arizona senator. McCain yesterday solidified his status as favourite to win the Republican nomination by winning nine of 22 states in yesterday's Super Tuesday primaries. He leads his nearest rival, Mitt Romney, in the delegate count 570 to 251. But later in the day, McCain...